HV20 gain [Archive] - DVXuser.com -- The online community for filmmaking

Verko

04-01-2007, 09:36 PM

My preliminary under-the-gun findings:

I got mine on Wednesday this week, had one day to mess with it before using it on a 3 camera shoot with 2 HVX's (couldn't find another HVX to rent with two hours notice).

For practice, I shot some of my son's school assembly on it; kids in white shirts with strong key lights and black drapes behind them are indeed a good test for exposure issues and gain. My process was interactive, as I was trying to quickly figure out what the HV20 was doing.

Spotlight mode - didn't compensate enough. Bringing down the "exposure" - not enough. Seems to affect shutter speed and aperture with some kind of unholy teamwork. Aperture priority mode - unusable for this situation. Gained up horribly. Again, unholy relationship between aperture and gain.

Cine-mode (the camera mode, same menu as shutter priority, not the frame rate) seemed to keep the camera from gaining up; the other modes would be adding grain I could even see in the LCD when I was on the dark background. I ended up only using the cine mode. I don't know if you can use it with 60i or not. Didn't try it yet. I like the 24F mode in any case, though it's a pain in the butt to remove pulldown with FCP/Cinema Tools.

100% zebra seemed pessimistic (95%?); in any case, transition to overexposure is surprisingly smooth. Very impressed with that. Yes, I know it's clipping at 107 or so, but 100% zebra did seem conservative.

I was really surprised to view the footage HD-SDI out from my Kona LHe. Happily surprised. Low light performance was much better than I expected too.

My 3 camera shoot the next day was three-angle green screen. 2 HVX, 1 HV20. I chose to shoot everything 24, as that is the only mode I had properly tested the HV20 at. I don't like interlacing for green screen anyway. The HV20 cut together quite well with the HVX's. I used it for one of the over-the-shoulder angles, as I find closer shots are more forgiving for lower-end cameras. Manual focus control worked fine with the LCD "enhanced". It's funny using such a small dial to control focus, but it worked. I wouldn't want to have to rack focus on it!

Definitely, test this thing before serious use (as with anything of course, but more so than regular professional gear). But I am very pleasantly surprised with what I can get out of it! Good tool for the toolbox and a great companion to the HVX.

Edit: Shutter speed in Cine-mode SEEMS locked where it should be, 1/48. Another reason to use this mode.

e-steve

04-01-2007, 10:45 PM

Based on this, I think I've kind of figure it out...(at least how to keep the gain constant)

1) Press the Func button
2) Go into Tv mode (shutter priority)
3) You can adjust the shutter here with the joystick
4) Press the Func button to turn off menu
5) Press the joystick (center)
6) Scroll down until you get to EXP (joystick down)
7) Press up once on the joystick, -/+ will turn white
8) Set EXP to 0 buy moving joystick left/right
9) Press the joystick (center)

- AGC should be off now...I am assuming you guys figure this out too...but wanted to spell out how I did it in case others may be wondering.

Did you guys notice the DOF when in Av setting it to 1.8? Not too bad, buy I just did a few tests sticking out my foot in front of me... LOL will test more on the road this week...

icicle22

04-02-2007, 04:47 PM

Edit: Shutter speed in Cine-mode SEEMS locked where it should be, 1/48. Another reason to use this mode.

My very early findings when in Cine-mode was that it was too blurry. It definitely did not look like 1/48. More like 1/24. I switched to TV mode and locked it at 1/48 and it looked much more "normal". I am not saying that your footage wasn't recorded at 1/48 but rather you may have somehow locked it there manually or your shooting environment never called for anything but that speed.

Anyone else seeing this?

Barry_Green

04-02-2007, 04:57 PM

I played with it a bit, and it seems to be really... odd. As in, it's always in auto-exposure mode, and you can choose to lock the shutter or you can choose to lock the aperture.

If you lock the shutter at 1/48, it'll change the aperture (and the gain) and not give you any clue as to what it's doing to you.

If you lock the aperture, it'll change the shutter as much as it wants, and maybe the gain too.

I believe you can lock exposure completely by using the shutter priority mode (to force 1/48) and then pressing the joystick to get the EXP window up and pressing "up" to bring up the exposure override window. That appears to give you some degree of manual control. However, there's no indication as to what you're changing. Are you changing gain? Iris? ISO? No way to know. Is the camera gained up to max, or running at 0dB? No way to know.

I put on the "data code" and recorded and played back, and that lets you see what it chose for shutter and iris, but only after-the-fact. And still no indication of what the gain was.

Then, what's really weird, is that it can handle very dark to very bright conditions without bringing ND filters into play. There are no ND filters in it, near as I can tell, unless there's some sort of odd internal variable ND, which I would seriously doubt. So -- what is it doing? Obviously it's using positive gain in low light situations, but does it have variable negative gain?

Normally the iris is only allowed to range down to f8.0; it's rare to see it go any lower. And at f/8.0 in broad daylight, you'd need something like 1/2000 shutter to get proper exposure. Yet it'll show 1/48th. So what's it doing? My guess is that it's internally adjusting the ISO, which is basically the equivalent of applying a whole lot of negative gain.

So -- what does that mean? What should you use? When's the "zero point" of gain, and how do we find that and use it? One poster on DVInfo suggested covering the lens cap and then bringing up EXP; at that point it should be fixed at maximum gain, and you can turn it down from there -- but how far? Where's zero?

Until I can find out more info, I'm inclined to think of the HV20 as an auto-exposure-only product, and you just can't know what it's doing to your footage. Use Shutter Priority mode, lock the shutter at 1/48, and everything else (aperture and gain and ISO) is ... well, you get what you get, basically.

AuditoryVisuals

04-02-2007, 07:14 PM

Very weird. Maybe it's adjusting the gamma? Could it be doing that?

Gordon Prince

04-02-2007, 10:06 PM

I believe you can lock exposure completely by using the shutter priority mode (to force 1/48) and then pressing the joystick to get the EXP window up and pressing "up" to bring up the exposure override window. That appears to give you some degree of manual control. However, there's no indication as to what you're changing. Are you changing gain? Iris? ISO? No way to know. Is the camera gained up to max, or running at 0dB? No way to know.

And so what? If it gives you the same result... What for I need to know the backyard? The way is to have a real automatic film crew for free. Without to pay more than what the filmmaker have to pay for the camera. This is what we might call a real indy camera.

rapsucks

04-02-2007, 11:02 PM

I guess the real test would be to see some footage in different situations--with the settings recorded, if possible.

There are always the old tricks of putting your hand in front of the lens to lock the iris open, but what makes me nervous is that you don't seem to have any direct control over the gain. I don't know about you, but that's a little scary to me.

Like I said, though, the truth is in the footy. If it looks good under a variety of situations, then we might have a winner in the high-end consumer division.

Barry_Green

04-02-2007, 11:51 PM

And so what? If it gives you the same result... What for I need to know the backyard?
Well, if you're comfortable with the camera deciding that your shot needs 18dB of gain in one circumstance but not another, and not telling you about it, then... well, I guess that's okay for you. But a lot of us would appreciate knowing how the thing works so we can keep a lid on what it's doing, so there are no "surprises" in the editing suite.

Barry_Green

04-02-2007, 11:53 PM

I guess the real test would be to see some footage in different situations--with the settings recorded, if possible.
But there aren't any settings. So how do you record 'em? That's what I'm getting at -- there's no way to know what the thing is doing. I would have thought it'd show the gain level in the data code; my old VX1000 did that, but I can't find out how to make the HV20 deliver that information.

If it would display the gain level, we'd be well on our way to figuring out all its methods and we could get a handle on how to make it perform to its best. But without the proper feedback... I don't know what to do next. Suggestions?

rapsucks

04-03-2007, 12:05 AM

Don't you hate it when the device thinks that it's smarter than you are?

You're right--there should be at least a meter or something. That way even if you can't manually control it you can see what it's doing and maybe trick it into doing what you want.

Barry_Green

04-03-2007, 12:38 AM

Well, again, lots of users may not even care, but I'd sure like to know. I wonder if it works with Console? And if Console gives that feedback? Never tried it...

jenningsp

04-03-2007, 01:33 AM

i don't have my HV20 yet. but from my reading i've worked out this chart. could one of you test this out...

in TV mode.
put in in either spotlight or auto mode then cover the lens (make the picture pitch black) wait till the camera adjust then push the exposure button.

put it in auto mode to control the gain.
i'm not sure if the gain goes up to 18db. it might only go up to 15db. if that's the case then 0 = 15db, -1 = 13.5db... -9 = 1.5db.

-11 = 1.5db
-10 = 3db
-9 = 4.5db
-8 = 6db
-7 = 7.5db
-6 = 9db
-5 = 10.5db
-4 = 12db
-3 = 13.5db
-2 = 15db
-1 = 16.5db
0 = 18db

put it in spotlight mode to control the aperture.

-9 = 8
-8 = 6.8
-7 = 5.6
-6 = 4.8
-5 = 4
-4 = 3.4
-3 = 2.8
-2 = 2.4
-1 = 2
0 = 1.8

when i say 0 i mean where it starts from in the exposure setting. it should start from that point but it could actually be +11. i'm not sure. do you understand what i mean?
this is just theory for now. the values could all be wrong. i'll fine tune it all when i get my HV20 :)

rawfa

04-03-2007, 04:05 AM

I've said that in another thread but what really worries me is the lack of BASIC manual control. You can either control aperture or shutter, and the gain does whatever it feels like?! This is crazy. I mean, you could try to put some ND filters on the camera but the internal controls would probably interpret this as low light and boost the gain. There's gotta be solution for this.

Barry_Green

04-03-2007, 09:46 AM

this is just theory for now. the values could all be wrong. i'll fine tune it all when i get my HV20 :)
But where do you get these numbers from? And how will you fine tune it? There's no feedback on the camera that I found. There's no way to know what the numbers are.

Barry_Green

04-03-2007, 09:52 AM

I've said that in another thread but what really worries me is the lack of BASIC manual control. You can either control aperture or shutter, and the gain does whatever it feels like?! This is crazy.
Crazy? This is consumer. The HV20 is a consumer camera. The JVC HD1 was pretty similar, you couldn't actually control both shutter and aperture at the same time and lock it, IIRC.

The HV20 is great for what it is, but keep in mind this is a tiny pocketcam consumer camera. It is not by any stretch of the imagination a professional tool. I am, frankly, shocked at what it does offer: it has some zebras, it has a peaking setting, it has manual white balance, and it even has a manual audio control! That's light years beyond what you find in most consumer cameras. But it doesn't, as near as I can tell, give any usable feedback for what you're doing with the exposure.

I mean, you could try to put some ND filters on the camera but the internal controls would probably interpret this as low light and boost the gain. There's gotta be solution for this.
Why does there "gotta be a solution for this"? I mean, look at my Nokia N93 videocam/phone: it controls the exposure by itself, I only have an EV +/- setting of -2 to +2 or so. I don't know what it's doing, whether it's adding gain or changing the shutter, and as a consumer, do I care? Not really.

HV20 is a consumer camera, folks. Made for consumers. Sold to consumers. It's not a professional tool, and it doesn't have professional control. Don't try to make it into something it's not.

Now, that said, I'm very happy with it in all ways but this one. If I could figure out how to get complete exposure control and understanding of the exposure, I think some amazing things could be done with it; at the price point it's unparalleled. At twice the price it'd still be a steal, but at twice the price I'd DEMAND proper exposure control. At this price point I'm not complaining about the exposure control, I'm just casting about for ideas as to if anyone has suggestions or has worked with a system like this and has insight they can offer.

rawfa

04-03-2007, 10:09 AM

This might help http://www.dvinfo.net/conf/showthread.php?t=85370
I don't have the HV20, so I cannot try this, but apparently it's the way to go around this "problem".

rawfa

04-03-2007, 10:12 AM

I'm with you, Barry. This is not a pro camera. I cannot image the face of the people I work for if I showed up with a HV20 instead of the A1 one day. But from what I've seen and read, this could be one heck of an amazing B-camera. Actually, I have absolutely no doubt at all it'll be used by many as their main camera with amazing results. God know what I would have given to have something like this when I was studying film.

jenningsp

04-03-2007, 10:38 AM

But where do you get these numbers from? And how will you fine tune it? There's no feedback on the camera that I found. There's no way to know what the numbers are.

i got these values from a few different places. different forums and the HV20 manual.
none of it was specific. i am estimating alot of it...

but test it out. from my current understanding, it's all accurate.
barry, do some tests according to my chart and you'll see if i'm wrong :)

Barry_Green

04-03-2007, 10:39 AM

I gotta try some more of that experimentation when I get the HV20 back. Between staring at the aperture blades and monitoring the waveform in DV Rack maybe I'll at least be able to get to the bottom of the gain issues!

Barry_Green

04-03-2007, 10:45 AM

and the HV20 manual.
What info in the manual? I've searched the manual, and the term "gain" doesn't even show up in it; nor does "AGC". Is there some point where it mentions the limit of gain (i.e., that it's capable of a maximum of 18dB or something?) That would be key information to have.

jenningsp

04-03-2007, 10:54 AM

the maximum gain is still unknown to me. as stated in my previous post. it could be 18db or 15db. i would bet on 18db

one thing i do know is that the gain is increased by 1.5db increments. this is stated in the dvinfo post mentioned by rawfa.

the information i got from the HV20 manual is the aperture increments. it lists all the possible aperture values.

in aperture priority mode, does it tell you the level of gain?
if it does then can't you see the max gain level?

Barry_Green

04-03-2007, 11:08 AM

the maximum gain is still unknown to me. as stated in my previous post. it could be 18db or 15db. i would bet on 18db
Why? Why would it be limited to 18 or 15? Why not 9, or 36, or 60? There's no indication given. So I'm asking for if there are any concrete sources of verified information.

in aperture priority mode, does it tell you the level of gain?
if it does then can't you see the max gain level?
I haven't found any way that it ever tells you anything about gain. As in, whether it's using any or not, whether it's positive or negative, whether it even has the concept of gain (which certainly it does, but what I'm saying is: the manual doesn't even acknowledge gain). So -- does it use gain (certainly it does) and if so, to what degree? When? In what increments? To what maximum?

Can you lock it out? How can you know what the current gain setting is?

Those are burning questions for those of us wanting to extract the maximum image from this little wonder without getting burned by grainy gain.

jenningsp

04-03-2007, 11:55 AM

barry, there is currently no conclusive data. nobody has done the tests.

i am going to do some test when i get my HV20 - date still unknown :(

but i think my charts for the "cover up the lens and push the exposure button trick" in auto or spotlight mode are accurate :) why? because i have shiny pants, that's why.

Gordon Prince

04-03-2007, 12:20 PM

Well, if you're comfortable with the camera deciding that your shot needs 18dB of gain in one circumstance but not another, and not telling you about it, then... well, I guess that's okay for you. But a lot of us would appreciate knowing how the thing works so we can keep a lid on what it's doing, so there are no "surprises" in the editing suite.

Understood. I won't be so comfortable despite your good humor. Nevertheless, this technical talk is annoying for some of us where I am included. I'm just a novice but a director novice. Not a techie. For me what counts it's the result. If you might imagine how it seems odd (= really crappy) some of the content that we can watch crossing these pages... Even with all the technical requirements... You could figure out why this technical talk seems completely out of range for the good filmmaking.

However, to have manual control is more than normal. I couldn't get it: after all, is there manual controls or not? I am a noob and I'm fine. So please be patient with who won't or cannot ever follow your technical talks. And answer it for dummies as well like me.

Barry_Green

04-03-2007, 12:36 PM

There's SOME manual control. But not complete manual control. That's what the discussion is about -- we're trying to figure out how to understand what the thing does, so we can know if it has proper manual control and if we can keep things like electronic gain under control.

Gordon Prince

04-03-2007, 12:42 PM

Okay but isn't there, at the same time, total control on aperture and 1/48 shutter (guaranteeing the gain as low as possible)?

I don't want to mean this or that gain mark. For me, they're just numbers. I don't give a damn if it is a 365 or a 563 there, only as low gain as possible. Avoiding (all the) grain, for instance.

Is it possible to assure that?

Barry_Green

04-03-2007, 01:52 PM

Duct Tape Films

04-03-2007, 02:00 PM

Gordon Prince

04-03-2007, 03:11 PM

No. That's the problem, in a nutshell. You can only assure shutter speed, OR aperture, but not both.

So you can set it to 1/48th, but you might get all sorts of gain in your picture, without you even knowing it.

OR, you might force the iris to f/2.8 with (presumably) no gain, but then your shutter speed might change off of 1/48 (again, without you knowing it).

Now you see why we're concerned about finding out the truth, right?

Okay. But doesn't these posts help at all? You said no word on these tips.

Other hints there go always to the same thread destination (probably the best way to answer it):

http://www.dvinfo.net/conf/showthread.php?t=88596

http://www.dvinfo.net/conf/showthread.php?t=87901

Here is another one:

http://www.dvinfo.net/conf/showthread.php?t=90064

Based on this, I think I've kind of figure it out...(at least how to keep the gain constant)

1) Press the Func button
2) Go into Tv mode (shutter priority)
3) You can adjust the shutter here with the joystick
4) Press the Func button to turn off menu
5) Press the joystick (center)
6) Scroll down until you get to EXP (joystick down)
7) Press up once on the joystick, -/+ will turn white
8) Set EXP to 0 buy moving joystick left/right
9) Press the joystick (center)

- AGC should be off now...I am assuming you guys figure this out too...but wanted to spell out how I did it in case others may be wondering.

Did you guys notice the DOF when in Av setting it to 1.8? Not too bad, buy I just did a few tests sticking out my foot in front of me... LOL will test more on the road this week...
i don't have my HV20 yet. but from my reading i've worked out this chart. could one of you test this out...

in TV mode.
put in in either spotlight or auto mode then cover the lens (make the picture pitch black) wait till the camera adjust then push the exposure button.

put it in auto mode to control the gain.
i'm not sure if the gain goes up to 18db. it might only go up to 15db. if that's the case then 0 = 15db, -1 = 13.5db... -9 = 1.5db.

-11 = 1.5db
-10 = 3db
-9 = 4.5db
-8 = 6db
-7 = 7.5db
-6 = 9db
-5 = 10.5db
-4 = 12db
-3 = 13.5db
-2 = 15db
-1 = 16.5db
0 = 18db

put it in spotlight mode to control the aperture.

-9 = 8
-8 = 6.8
-7 = 5.6
-6 = 4.8
-5 = 4
-4 = 3.4
-3 = 2.8
-2 = 2.4
-1 = 2
0 = 1.8

when i say 0 i mean where it starts from in the exposure setting. it should start from that point but it could actually be +11. i'm not sure. do you understand what i mean?
this is just theory for now. the values could all be wrong. i'll fine tune it all when i get my HV20 :)
This might help http://www.dvinfo.net/conf/showthread.php?t=85370
I don't have the HV20, so I cannot try this, but apparently it's the way to go around this "problem".

Barry_Green

04-03-2007, 04:38 PM

It's not a megaton bomb though. It's just a level of control that I hope it has, but can't figure out yet. The HV20 is still going to be enormously popular, and deservedly so. This is the only fly I've found in its ointment so far, and I still have to say that for what I was expecting on a $925 consumer camcorder, it's got a LOT more than I ever thought it would! Manual audio control, zebras, peaking, and manual white balance, as well as the ability to lock 1/48 shutter speed... all very welcome and very surprising. If we can just figure out how to lock exposure with no artificial gain, it'll offer all the basic functionality one would need.

Barry_Green

04-03-2007, 04:40 PM

Okay. But doesn't these posts help at all? You said no word on these tips.
The one that looks most promising is Dennis Wood's post at the end, so that's what I intend to try once I have some time, the waveform monitor, and all the appropriate tools. We can probably get to the bottom of it; I was just really hoping someone had some printed documentation that describes how it actually works.

AuditoryVisuals

04-03-2007, 05:11 PM

I am, frankly, shocked at what it does offer: it has some zebras, it has a peaking setting, it has manual white balance, and it even has a manual audio control! That's light years beyond what you find in most consumer cameras

Barry, a lot of consumer cameras have manual white balance mine cost $300 and it has manual white balance, AGC off, apperture control (I'm prosuming) and shutter speed control all at the same time. Using a feature for slowing down the framerate and shutterspeed at the same time. I was even able to get 24fps out of it with controling the lighting and exposure compensation. But it could change any second. I could count the frames in a second to 24 after capturing too. It was all a blur that was incredibly grainy though. And I couldn't have any manual control while doing this. JVC GR-D250.

But the HV20 is an advanced camera. Top of the consumer cameras that Canon has.

Panasonic's got gain control on pretty well all of their camcorders.

Okay but isn't there, at the same time, total control on aperture and 1/48 shutter (guaranteeing the gain as low as possible)?

I don't want to mean this or that gain mark. For me, they're just numbers. I don't give a damn if it is a 365 or a 563 there, only as low gain as possible. Avoiding (all the) grain, for instance.

Is it possible to assure that?

No. That's the problem, in a nutshell. You can only assure shutter speed, OR aperture, but not both.

So you can set it to 1/48th, but you might get all sorts of gain in your picture, without you even knowing it.

OR, you might force the iris to f/2.8 with (presumably) no gain, but then your shutter speed might change off of 1/48 (again, without you knowing it).

Now you see why we're concerned about finding out the truth, right?

Haven't you tried the Spotlight mode yet? It said at DVinfo it would set the gain to zero.

Sumfun

04-03-2007, 05:14 PM

and I still have to say that for what I was expecting on a $925 consumer camcorder, it's got a LOT more than I ever thought it would!

Barry, where did you find the camera for $925? Lowest I found was $1069.

Barry_Green

04-03-2007, 05:21 PM

Haven't you tried the Spotlight mode yet? It said at DVinfo it would set the gain to zero.
But how do you know? Says who? How do you verify? I saw that post, but I didn't see anything that demonstrated why they claimed it was fixed zero gain.

Spotlight mode is supposed to open the aperture as much as possible to get the shallowest DOF look possible. Nothing in the description says it's limited to 0 gain.

Barry_Green

04-03-2007, 05:21 PM

Barry, where did you find the camera for $925? Lowest I found was $1069.
www.mediasupplystore.com (http://www.mediasupplystore.com), an authorized dealer.

jenningsp

04-03-2007, 10:40 PM

Gordon Prince

04-04-2007, 09:00 AM

I'm adding the same plead. Barry, you're the man.

Sumfun

04-04-2007, 10:58 AM

www.mediasupplystore.com (http://www.mediasupplystore.com), an authorized dealer.

Thanks for the referral, Barry. I don't know how you found them, but I'm glad you did. Spoke with Michelle and got great service.

For others who want to order, the $925 price is a promotion that's only good through April 9. (I'm sure the street price will come down, but it might take a while to get that low). They're currently sold out, but they're getting 2 shipments in a week.

icicle22

04-04-2007, 03:00 PM

And I paid $940 for mine! I feel ripped off! :)

Barry_Green

04-04-2007, 03:58 PM

I don't know how you found them, but I'm glad you did.
Found 'em through a referral right here on DVXUser.com!

Gordon Prince

04-04-2007, 05:58 PM

Mr. Barry, any update on your findings? Here's a whole community of poor creative filmmakers waiting.

Barry_Green

04-04-2007, 06:28 PM

It's on loan to somebody else right now. I would have liked to delve into this today but I don't have the cam right now.

AuditoryVisuals

04-04-2007, 07:24 PM

But how do you know? Says who? How do you verify? I saw that post, but I didn't see anything that demonstrated why they claimed it was fixed zero gain.

Spotlight mode is supposed to open the aperture as much as possible to get the shallowest DOF look possible. Nothing in the description says it's limited to 0 gain.

Where'd you hear that? Who told you that? Are you going to cite your sources? I looked in the manual and couldn't find any info on the Spotlight mode except for "use this mode to record spotlit scenes". And I don't know how this man has come to this conclusion. But what does a narrow DOF have to do with a spotlight? It would seem more logical to darken the image if the camera just want's to brighten up the dark background and blow out the main subject. And with no gain you could have a larger aperture and a narrower DOF too so it must not decrease the aperture. It could just be increasing the shutter speed though, but it seems like they would want less grain and "sacrafice" the sharpness. Shake your hand in front of it. If it stutters and looks choppy it's increasing the shutter speed. If it's fluid and with a motion blur, perhaps it's not. And see if the DOF changes after you switch from having a miminum aperture to the spotlight mode.

Anyway, my question was did you try it? Take it into the dark and change the exposure compensation and see if there's grain. If it's limited to zero it won't increase.

If you didn't try it, please do when you get it back.

Barry_Green

04-04-2007, 09:59 PM

DOH! I misfired some neurons, I was thinking of "portrait" mode, not "spotlight." Sorry!

But even so, there's still no mention of gain or control of gain in spotlight mode.

The thing about the exposure dial is, if you're in the dark it'll already be maxxed out. You don't always get -11 to +11, sometimes when you press the EXP button it starts out already at the top of the scale and can only go down from there; that's probably where it would start in any mode if you started in the dark.

Gordon Prince

04-05-2007, 04:39 AM

Dummies here, Mr. Barry. Total manual control from your findings or not?

Barry_Green

04-05-2007, 03:52 PM

Okay, started playing around with it, and have been able to determine a few things.

First, putting it in spotlight mode does indeed cap the gain at 0dB; even with the lens completely covered it won't go into gain. That's nice; problem with it is, you don't know what your shutter or iris are. In my testing the shutter could go to 1/15 in spotlight mode.

As for putting it in shutter priority and capping the lens to force the gain to a certain level, that also works, but with way more gain than I was expecting. With the lens capped, on 1/48, you end up with 27dB of gain! Each click down on the wheel appears to take the gain down by 1.5dB, and by the time you reach the minimum exposure level (-11) you still have 9dB of gain in the signal.

Haven't explored what cine exposure mode is really doing yet.

Gordon Prince

04-05-2007, 04:14 PM

:thumbup:

Okay, started playing around with it, and have been able to determine a few things.

First, putting it in spotlight mode does indeed cap the gain at 0dB; even with the lens completely covered it won't go into gain. That's nice; problem with it is, you don't know what your shutter or iris are. In my testing the shutter could go to 1/15 in spotlight mode.

No further than that? 1/48?

As for putting it in shutter priority and capping the lens to force the gain to a certain level, that also works, but with way more gain than I was expecting. With the lens capped, on 1/48, you end up with 27dB of gain! Each click down on the wheel appears to take the gain down by 1.5dB, and by the time you reach the minimum exposure level (-11) you still have 9dB of gain in the signal.

Haven't explored what cine exposure mode is really doing yet.

Cine exposure mode + 1/48, what's the gain?

Barry_Green

04-05-2007, 04:23 PM

Messed around with cine mode, and it seems like it always wants to run at 1/48th, which is good.

For the record, all this testing is done in HDV PF24 mode, so true 24P acquisition.

In cine mode it normally runs at 0dB of gain and 1/48 shutter; under lower light conditions it can climb to 9dB of gain and the shutter can actually go as slow as 1/8. Definitely not what you want, if trying to emulate the look of film, so be careful with it especially under lower-light conditions. In normal light conditions and pressing the EXP all the way positive, the shutter can go as low as 1/24.

So far I think the only exposure system that's actually trustable for the film look is Tv (shutter priority); I just have to figure out a way to ensure that it's starting at 0dB of gain...

Barry_Green

04-05-2007, 04:57 PM

With lens capped, in CINE exposure mode, and 24P, I stepped through the range of exposure options. The exposure dial goes from +3 to -11.

+3: 1/8 f/1.8 10.5dB?
+2: 1/15 f/1.8 10.5dB?
+1: 1/15 f/1.8 9dB
+0: 1/24 f/1.8 9dB
-1: 1/24 f/1.8 7.5dB
-2: 1/24 f/1.8 6dB
-3: 1/24 f/1.8 4.5dB
-4: 1/24 f/1.8 3dB
-5: 1/24 f/1.8 1.5dB
-6: 1/24 f/1.8 0dB
-7: 1/24 f/1.8 0dB
-8: 1/30 f/1.8 0dB
-9: 1/30 f/1.8 0dB
-10: 1/30 f/1.8 0dB
-11: 1/48 f/1.8 0dB

So -- there's a way that you can force 1/48 and 0dB of gain -- set the HV20 in CINE mode, cap the lens and lock the exposure, then force the exposure dial all the way down to -11. Problem is, you've now taken away the iris as a means of setting exposure, so how do you account for changing light conditions? You could do it with an arsenal of ND filters I guess...

Barry_Green

04-05-2007, 05:29 PM

In exterior conditions, pointed at a moderate sky (not blazing sunlight, but still a moderately bright sky) and 24P/CINE mode, it defaulted to F/5.6 at 1/48. I then locked exposure and ran through the gamut.

+11: 1/48 f/4.8 0dB
+10: 1/48 f/4.8 0dB
+9: 1/48 f/5.6 0dB
+8: 1/48 f/5.6 0dB
+7: 1/48 f/5.6 0dB
+6: 1/48 f/5.6 0dB
+5: 1/48 f/5.6 0dB
+4: 1/48 f/5.6 0dB
+3: 1/48 f/5.6 0dB
+2: 1/48 f/5.6 0dB
+1: 1/48 f/5.6 0dB
+0: 1/48 f/5.6 0dB
-1: 1/48 f/5.6 0dB
-2: 1/48 f/5.6 0dB
-3: 1/48 f/6.7 0dB
-4: 1/48 f/6.7 0dB
-5: 1/48 f/8.0 0dB
-6: 1/60 f/8.0 0dB
-7: 1/75 f/8.0 0dB
-8: 1/90 f/8.0 0dB
-9: 1/100 f/8.0 0dB
-10: 1/120 f/8.0 0dB
-11: 1/150 f/8.0 0dB

I have no explanation fo rthis one, I have no idea what it was doing between +9 to -1, there's no discernable difference in the exposure data, but there's a massive difference in the recorded image. The aperture and shutter and gain didn't appear to change at all, but the image definitely got much brighter.

My question is -- is there some sort of "adjustable ISO" system that the camera goes through? Like gain, but not classified as gain? A "stealth" gain? I stared in the iris while walking it through its range of - to +, and couldn't see any evidence of any neutral density filters moving into place or anything (nor could I see how that would even be practical!) So what is it doing? I suspect it's some sort of CMOS ISO adjustment, which is in effect "gain", but not classified according to the data code as "gain".

I don't know what that means though, as far as quality of image. From experimenting with it, it seems like the CINE system does prefer 1/48 when it can get it, but you can definitely get shutter speeds way out of range when using CINE mode (anywhere from 1/150th all the way to 1/8th). If you want to know for sure you're getting 1/48th, the only way to assure yourself of that is to use the Shutter Priority mode.

Barry_Green

04-05-2007, 05:51 PM

When using Shutter Priority (Tv) mode: starting with the lens capped is useless, because it starts with 27dB of gain. So you have 1/48th, but even if you push the exposure all the way down to -11 you'll still have 12dB of gain...

Polle

04-05-2007, 07:47 PM

Wow, thanks Barry! Even though I won't own a HV20 (Maybe later, as a tapedeck for the ordered XHA1), this was like a peek into a masterclass.

:)

rapsucks

04-05-2007, 08:41 PM

Barry, you're the man.

Does the camera at least tell you what it is doing so far as aperture, shutter speed, and gain are concerned? In other words, were those numbers easy to find for any particular setup? This would at least prevent you from being surprized at the result of any image.

If there was only a way to lock any or all of the variables at will. You could lock gain at 0db, shutter at 1/48, and then adjust the iris for exposure. That might be asking too much from a $1,000 camera, but my thinking is this: they already have the control system in place for the camera to adjust all of those three variables--why not just open that control to the user?

But I guess you can't always get what you want.

Barry_Green

04-05-2007, 08:48 PM

Does the camera at least tell you what it is doing so far as aperture, shutter speed, and gain are concerned?
No, not at all. It gives you none of that info if you're using any of the programs. The only feedback you can get is if you use Aperture Priority (which will tell you the aperture, but nothing else) or Shutter Priority (which will tell you the shutter, but nothing else).

In other words, were those numbers easy to find for any particular setup?
No, it was a royal pain in the butt. You can find out shutter speed and aperture after the fact, by turning on the data code and playing your footage back, but it won't show you gain at all. The *only* way to find out what gain you were at is to take the tape out of the HV20 and play it in another HDV camcorder that DOES display the gain in the data code (i.e., it's recording the gain info to the tape, but its display system won't show you that data!) I dug up a Sony HDV camcorder, turned on the data code, and then played the HV20 tape in it to find out what the gain was. So I had to spend a couple of hours running the HV20 through every possible configuration, narrating it the whole way, and then playing it back on the HV20 to find out what the shutter speed was (because the Sony HDV camcorder doesn't recognize and won't show 1/48 or 1/24; it lies to you and says it's 1/30 or 1/15!) So playing on the HV20 is the only way to figure out what the real shutter speed was, but it's useless for figuring out the gain. So I'd make notes on what all the shutter speeds were, then have to rewind the tape and play it on the Sony to get it to tell me what all the corresponding gain values were.

But you cannot know what the parameters are while you're shooting. If this were a $2500 camcorder I'd call that a fatal flaw. But for a $925 camcorder, I'm still grinning that I was able to figure it out, and that it's controllable enough that if you jump through enough hoops you can sort of get what you want from it. It's like overclocking a CPU, or putting a hopped-up exhaust system on your Honda Civic; it's totally a game of beat-the-camcorder... :thumbsup:

If there was only a way to lock any or all of the variables at will. You could lock gain at 0db, shutter at 1/48, and then adjust the iris for exposure
That's what pro/prosumer cameras are for. The HV20 isn't anywhere near that same class, it's a little pocket-cam. Can make some pretty pictures, but in no way is this little cam comparable to an XHA1 or DVX as far as controls and feedback.

I'm thinking that if you wanted to actually use this in any sort of controlled circumstance, you might have to lock it at 1/48 & f/2.8, and then just use a stack of ND filters to control exposure. I'm almost wondering if one of those variable-ND filters might be the way to go... http://www.singh-ray.com/varind.html (of course, that filter costs half as much as an HV20, so that's not a good solution for those who'd be buying an HV20!)

Barry_Green

04-05-2007, 09:10 PM

Y'know, the one way I've been able to find a common baseline/ground for the HV20 is to completely cap the lens, so you know exactly what the HV20's going to expose at in any circumstance, right? Well, I'm thinking... the ultimate HV20 accessory would be some sort of light source that you could clamp onto the front of the lens, that emits a certain # of lumens of light (whatever the appropriate # is) in order to cause the HV20 to default to 1/48 & f/1.8 at 0dB. So you'd put on this thing to the front of the lens and tell the HV20 to expose, and it'd measure the incoming light and set for 1/48 & f/1.8, right? Then you could lock the exposure there, and have full use of the EXP range and it should only be affecting the iris at that point.

I wonder if I could figure out some graphic to display on a laptop, or if there's a cell phone LED that would emit enough light, or... I dunno, just thinkin'... for example, I brought up the B&H Photo site on my Dell 2405, and stuck the HV20 to where it was butted up against the screen, so the whole sensor is filled with the projected white light. Then I locked exposure using Tv(1/48). And I found I could get nearly the full range of exposure, from f/1.8 down to f/5.6 (but deep into f/5.6, I can't explain that, -2 to -11 all show f/5.6 somehow) and all of it at 0dB of gain. That's practically useful. Only thing is, you'd have to do this every time you moved into camera mode, every time you turned the camera on, etc. So you'd need a portable system (which is why I'm wondering if you could display something on your cell phone LCD that fills the screen and provides enough light to move the HV20 into middle-ground exposure, thus giving you the full range...)

Barry_Green

04-05-2007, 09:32 PM

Okay, so here's the new test -- I used my Nokia N93 phone's web browser to bring up Yahoo (a mostly-white screen) and used that as a "lens cap" on the Canon. Put it in CINE mode and locked exposure, then run through the gamut.
+11: f/1.8 3dB 1/24
+10: 1.8 0dB 1/24
+9: 1.8 0dB 1/24
+8: 1.8 0dB 1/30
+7: 1.8 0dB 1/30
+6: 1.8 0dB 1/30
+5: 1.8 0dB 1/48
+4: 2.0 0dB 1/48
+3: 2.2 0dB 1/48
+2: 2.4 0dB 1/48
+1: 2.6 0dB 1/48
0: f/2.8 0dB 1/48
-1: f/3.1 0dB 1/48
-2: 3.4 0dB 1/48
-3: 3.7 0dB 1/48
-4: 4.0 0dB 1/48
-5: 4.4 0dB 1/48
-6: 4.8 0dB 1/48
-7: 5.2 0dB 1/48
-8: 5.6 0dB 1/48
-9: 5.6 0dB 1/48
-10: 5.6 0dB 1/48
-11: 5.6 0dB 1/48

This might actually be workable. It's a field solution, it forces it to a set level, and you have usable range from -11 all the way up to +5. That's not bad. I'll have to try it in the field and see how practical it is outdoors... :thumbsup:

Jason Ramsey

04-05-2007, 09:49 PM

Barry_Green

04-05-2007, 10:05 PM

Tried it with my phone, loading up a JPG of pure white. It gave slightly more usable range, anything from -11 up to +6. I'm almost happy with that, but it'd be nice if I could get some additional range...

jenningsp

04-05-2007, 10:18 PM

Barry,

it seems that in Photo mode, you can view the shutter speed value and the apature value and the manual exposure value - all at the same time... that's what it looks like in the manual on page 17. can you use this?

jenningsp

04-05-2007, 10:23 PM

if it works, then you could just take a photo of your live stream, then check what all your values where in photo mode...

and you get a histogram!

Dennis Wood

04-05-2007, 10:32 PM

I did some experiments a few days ago and came up with this:

I was a bit concerned about manual control after trying out the HV20 tonight. My concerns are somewhat allayed after doing some experimentation. If someone comes out with a camera with the HV20 imagery, and the GS400 controls...look out. After getting used to that "consumer" cam's manual controls, the HV20 is a bit of a disappointment. Whoever puts the HV20's 24p imagery in a Panasonic GS400-like chassis will have a runaway hit product with the prosumer crowd.

In any case, here's part 1 of a mulit-part post on using the HV20 as an adapter cam. I placed the HV20 in shutter priority mode (TV), pressed the joystick to bring up EXP control and toggled it on. I went from -11 to +11 and then observed the aperture blades directly looking through the lens both with an LED headlamp, and then at an angle with overhead light. It is very apparent that the adjusment gradient will vary depending on the auto exposure level the camera has dialed in when you engage exposure control.

Based on my initial observations, here is what I would suggest for adapter use shooting 24P.

1. Set zebras at 70%
2. Set camera to 24P mode
3. Switch to TV mode, and set at 1/48s
4. Frame a shot so about 50% of the frame is displaying zebras. This is so the cam is neither fully gained up, or fully stopped down. It's just an approx. baseline.
5. Press joystick and toggle EXP on.
6. At this point here is a rough guide to what the EXP settings correspond to.

-11 = Aperture 80% closed, ND2 fully engaged.
-6 = Aperture 80% closed, ND2 full disengaged, ND1 visible.
0 = Apeture fully closed, ND1 disengaged completely.
+5 = Aperture 50% open.
+11 = Aperture 100% open.

Max sharpnes for this lens is likley somewhere around +9 on this scale. If you engage EXP with TV on and shutter at 1/48s but the cam pointed zoomed in on a light, you'll see 100% aperture closed, and I'd guess 100% ND filter engagement too.

If you want at least a vertical flip, here are some pics (http://www.cinevate.com/phpBB2/viewtopic.php?t=518) of how to do it.

vidled

04-06-2007, 06:54 AM

Sounds like you need a lens cap with led's inside of it. A watch battery (hopefuly) and a button on the lens cap. It's a lens cap. But, press the button and it's your exposure cap. Sounds like a vidled thing...

Yes, I could make something like that, no problem.
Barry, how much luminocity spread can this thing have? Also, you mentioned that the Sony is mistakenly reporting the shutter speed; how do you know it is the Sony who is reporting this wrong, and not the Canon? Just curious if this was actually established that the Canon IS true 1/48 second.

Norbert

04-06-2007, 07:01 AM

Barry, you are the man for sure. Thanks for being so persistent about this. You seem to be working out a good way to get the most out of it. I haven't got my hands on an HV20 yet but my old Sony handycam apparently adds gain if you set the exposure to max. I looked into the lens and saw that the iris was wide open at max exposure and it didn't start to close until I stepped down 7 steps, so the last 6 steps are all just adding gain.

When you were talking about variable ND-filters to control exposure I couldn't help to think that maybe a 35mm adapter would be another way to do this. You'd have a manual iris ring on the lens on the adapter. But how should this be done? I recon the iris on the camera should be wide open and shutter speed should be locked and then you control the exposure with the lens on the adapter. Is there a way to open up the iris to fully opened without introducing gain on the HV20? Based on my tests with my old Sony I don't think you will get a bright picture enough with a 35mm adapter if you just open up the iris as much as you can and then don't go any further by adding gain.

Barry_Green

04-06-2007, 08:43 AM

Also, you mentioned that the Sony is mistakenly reporting the shutter speed; how do you know it is the Sony who is reporting this wrong, and not the Canon?
The Sony's an old FX1, almost three years old now, and it came out before there was such a thing as 1/48 and 1/24. So it doesn't have the capability to report those numbers.
Just curious if this was actually established that the Canon IS true 1/48 second.
That's one of the few things I can actually verify; according to the Canon's manual, yes it is 1/48. And you can manually select 1/48 or 1/24 in the Tv mode. So I am of the opinion that the Canon's telling the truth, it actually is 1/48, and that the Sony's translation/lookup table just doesn't have an entry for 1/48 so it reports the closest value it can find in its list (which would be 1/30 apparently).

Barry_Green

04-06-2007, 08:47 AM

-11 = Aperture 80% closed, ND2 fully engaged.
-6 = Aperture 80% closed, ND2 full disengaged, ND1 visible.

See, this is what puzzles me -- I couldn't see any evidence of there being a physical ND filter in there. I did a similar test, got under a very bright light and used a flashlight, and stepped through the whole raft of options, and I can see the aperture closing down fine but I never saw any evidence of any ND filters sliding into place... and how would it be able to execute a physical filter sliding into place in the middle of a shot? I don't get it. I mean, I'd like to understand this better, as the presence of some manner of ND filters would help explain what the heck is going on at the lower end of the scale, but I couldn't find any evidence of 'em. Did I just miss it somehow? Maybe I didn't have it stopping down far enough to engage 'em?

Also, as for variable ND filters -- the Singh Ray variable ND is $400. Er, that's a tad expensive for a $925 camcorder. But apparently the Singh Ray Vari-ND is merely a circular polarizer with a linear polarizer in front of it. So you could probably grab a circ-pol and a linear-pol off ebay cheaply, stick 'em together, and come up with a similar solution.

Barry_Green

04-06-2007, 08:51 AM

When you were talking about variable ND-filters to control exposure I couldn't help to think that maybe a 35mm adapter would be another way to do this. You'd have a manual iris ring on the lens on the adapter.
Yes, you could do this. But you shouldn't, because 35mm adapters usually only perform well at about f4 and above; stopping down below f/4 usually involves making the grain of the ground glass apparent, and the more you stop down the more visible the grain gets. You should be using the camera's own iris and ND filters to control exposure.

AuditoryVisuals

04-06-2007, 09:52 AM

Thanks for all the info Barry, very much appreciated.

Have you done any tests of what the aperture would be at full telephoto?

jenningsp

04-06-2007, 09:56 AM

zoom X - widest aperture

0 - 1.8
1 - 1.92
2 - 2.04
3 - 2.16
4 - 2.28
5 - 2.4
6 - 2.52
7 - 2.64
8 - 2.76
9 - 2.88
10 - 3

Dennis Wood

04-06-2007, 11:23 AM

Barry, if the you do the test at full wide zoom, it looks like the aperture stays slightly more open than if you zoom in 100% on a bright source. In other words, with the 50/50 zebras at 70% when locking exposure, -11 does not seem to completely close the aperture. Looking at an angle of about 45 degrees (using an overhead CF bulb) you can see the reflected light in the aperture opening change colour suddenly ..and it does it twice. I observed the exact same type of ND filter (2 stage that slides in) from the GS400 looking through the lens. An led cap would work perfectly with what I tried in TV mode. Instead of using zebras at 70% and locking exposure when 30-50% of the frame is in zebras, an LED array in the cap could be used combined with metadata viewing (on the other HDV cam) to absolutely set the baseline. I'd buy that cap!

Btw, the only way I could visuallize the aperture and ND filters was with the cam fully zoomed out. That brings the rear element forward so you can visualize it.

On the iris side of things, I haven't tested the HV20 at all for diffraction due to aperture blades etc, but I suspect like the other cams similar to it, f4 would give the sharpest image. I have observed some vignetting introduced from the video cam's aperture before when using an adapter, so some testing with your selection of 35mm lenses would be a good idea if you plan on stopping the camera down. The stinker with these consumer cams is you can't lock in f4 and dial in an internal ND...meaning if you're into the internal ND's you're also using the smallest (not ideal for image quality) aperture.

Barry_Green

04-06-2007, 12:20 PM

Didn't try it wide-angle, I'll have to try it that way.

For diffraction, it really tries to not go below f/8; you have to really, really push it before it'll go past f/8. Normally it'll start changing the shutter before it changes the aperture deeper than f/8, but you can make it happen, I've seen something odd like f/19 before but it was when I was tracking some seagulls and they went in front of the sun.

Bruce Morgan

04-06-2007, 07:46 PM

I can only suggest we shot color charts and faces at various light intensity.
Verbalize all dial settings .

And a set of pan shots past dark and light objects before going on a real shot ...
Then throw it up on a monitor .There is always someway to get comfortable with your equipment ..test ..test ..test
until you know this little beast ..you need a good monitor .

Emanuel

04-07-2007, 05:43 PM

Helpful and real useful valuable info for the upcoming HV20 users. 5 stars (EDIT -- done) thread.

ecking

04-07-2007, 08:20 PM

Is there a way the important sections about how to properly control the hv20 because of it's limited manual features can be put in a different thread and stickied? I'm not 100% sure if you guys found a way around the expose thing or not and I'm sure we'd all like to know the conclusions without reading 9 pages.

[rob]

04-08-2007, 06:22 AM

Hi,
I have two questions that I'm wondering if anyone knows.

1.) Regarding shutter speed, can the HV20 handle higher shutter speed like 1/250 or 1/500 in 25P/24P and Cinemode?

2.) Is it possible to do variable frame recording. Like recording 1 frame per minute?

Thanks

Artscroll

04-08-2007, 10:24 AM

rob, yes it can handle higher shutter speeds in 24p, I suppose 25p for PAL. You do this by setting the shutter speed in TV mode.

Cinemode, to me, appears to always have a locked 1/24 shutter, just my observations with my eyes.

1 frame per minute (timelapse) is not possible with the HV20 unless you capture to a laptop live via something like DV Rack, HD edition.

You could get 60 frames (almost three seconds of video) if you shoot a whole tape and speed it up in post. Lots of trouble just for 3 seconds though.

Barry_Green

04-08-2007, 11:41 PM

Cine mode attempts to keep the shutter locked on 1/48 as much as it can. It can go slower, under low light circumstances, but in adequate light it will stick to 1/48.

icicle22

04-09-2007, 01:04 PM

So you feel it will not want to go faster than 1/48 but will go slower if there is not enough light? I have found it going to 1/24 in s scenario that looked pretty good to me as far as available light is concerned.

Cine mode attempts to keep the shutter locked on 1/48 as much as it can. It can go slower, under low light circumstances, but in adequate light it will stick to 1/48.

[rob]

04-09-2007, 01:08 PM

Thank you Artscroll and Barry for your replies

Barry_Green

04-09-2007, 01:24 PM

It can go faster or slower depending on what it thinks the prevailing conditions are. I've found that I can lock it and keep it at 1/48 throughout the range of -11 to +5, but once you get to +6 it starts changing the shutter. Whether it "looked good to you" isn't the issue, it's what the camera needs that's the issue, and CMOS cameras and especially tiny-pixel CMOS cameras are not good at all at gathering light. I should do some comparisons against some of the other cameras to see what it's like; thing is, you don't really KNOW what it's doing, because it doesn't tell you. It might be running with 27dB of gain for all you know...

You can find out your shutter speed and aperture after-the-fact by turning on the Data Code in the display and playing your footage back. It won't tell you gain though.

Emanuel

04-09-2007, 03:42 PM

You Barry score into the neighbourhood (Canon) field... :thumbsup:

icicle22

04-09-2007, 07:21 PM

I understand Barry. I just thought you had determined 100% that the cinemode preset would not allow a higher shutter speed than 1/48.

It can go faster or slower depending on what it thinks the prevailing conditions are. I've found that I can lock it and keep it at 1/48 throughout the range of -11 to +5, but once you get to +6 it starts changing the shutter. Whether it "looked good to you" isn't the issue, it's what the camera needs that's the issue, and CMOS cameras and especially tiny-pixel CMOS cameras are not good at all at gathering light. I should do some comparisons against some of the other cameras to see what it's like; thing is, you don't really KNOW what it's doing, because it doesn't tell you. It might be running with 27dB of gain for all you know...

You can find out your shutter speed and aperture after-the-fact by turning on the Data Code in the display and playing your footage back. It won't tell you gain though.

Barry_Green

04-09-2007, 08:43 PM

No, I determined the opposite -- cine mode can definitely step outside of 1/48. But it really tries to stay at 1/48.

Only way to guarantee 1/48 is to use shutter-priority mode.

Dennis Wood

04-09-2007, 08:43 PM

Did some shooting with the Brevis and HV20 over the weekend. Playing the tapes back, (view data) I was able to lock in f 4.2 and f 5.6 using the TV mode/exposure method posted a page or two back. Shutter was locked a 1/48 and I used a 50mm lens at f4 for most of it. Had .9ND and CP 4x4 filter up front.

Our HV20 has a terribly non lens-centric image. It's skewed way to the right...and the first time I've seen this on a small cam. When framing the Brevis imaging elelment it's not a huge deal, but still strange to see in a small cam. It's not unusual on the HD100s.

Illya Friedman

04-10-2007, 04:57 AM

I received my HV20 just before I went on Vacation in March, and noticed all the same things you folks are describing. However, I purchased my camera specifically for it's size and holiday travel- not filmmaking. So these issues don't concern me. However, working in the field that I do- it's a curiosity.

However, getting this figured out should not be too difficult. Here's my theoretical approach, create your standard HV20 settings (Shutter Priority, Cine, whatever)- use the HDMI output and an HDMI to HDSDI converter and Leader 5700. Shoot a Chroma DuMonde, experiment by adding FC until you get the optimal "neutral" exposure point. Try both 3200 and 5600 and compare if they match.

Here's the trick- find a color chart that has a wedge that'll give you either 70 or 100% zebras at that optimal level, you may have to make something and may take some experimenting. In the field rate your light meter at that point to determine chart light FC (or exposure at your choice of ASA) and from that point you should be able to set your baseline neutral with a chart, light (probably ng gels for daylight), and zebras when shooting.

Should be a simple way to maintain that starting neutral point for maximum exposure control without gain or shutter involvement. You should be then able to confirm results with the FX1 or similar camera.

I'm totally slammed through NAB, but if no one else has done it by the end of April maybe I'll spend an hour or so and figure it out.

I.

Will this jet lag never end!

Illya Friedman

04-10-2007, 05:09 AM

Also, as for variable ND filters -- the Singh Ray variable ND is $400. Er, that's a tad expensive for a $925 camcorder. But apparently the Singh Ray Vari-ND is merely a circular polarizer with a linear polarizer in front of it. So you could probably grab a circ-pol and a linear-pol off ebay cheaply, stick 'em together, and come up with a similar solution.

I agree I'd bet it's just two polas. I think Tiffen sold the same thing many years ago. It might be possible to find one on ebay for less than half the money. You'd just need to add your own marks. I seem to remember even owning the Tiffen version but sold it with my CP-16R.

Emanuel

04-10-2007, 01:18 PM

Also, as for variable ND filters -- the Singh Ray variable ND is $400. Er, that's a tad expensive for a $925 camcorder. But apparently the Singh Ray Vari-ND is merely a circular polarizer with a linear polarizer in front of it. So you could probably grab a circ-pol and a linear-pol off ebay cheaply, stick 'em together, and come up with a similar solution.
I agree I'd bet it's just two polas. I think Tiffen sold the same thing many years ago. It might be possible to find one on ebay for less than half the money. You'd just need to add your own marks. I seem to remember even owning the Tiffen version but sold it with my CP-16R.BTW, any suggestion on useful links?

Norbert

04-11-2007, 07:51 AM

What I am interested in is a good way to get as much exposure range as possible at 0dB after locking the exposure in Tv mode... like the cellphone trick that Barry tried. Any tips on that would make a great sticky.

Dennis Wood

04-12-2007, 01:05 AM

If you set zebras at 70% and lock exposure with about 30% of the frame showing them, you'll get a range of +-11 with 0 corresponding to ~f4

I've finally worked out a reasonable work flow for pulldown removal (PC based) too.

rapsucks

04-12-2007, 01:36 AM

Do tell, Dennis.

Dennis Wood

04-12-2007, 02:08 AM

I'm hoping some AE experts can refine this procedure a bit. I'm using AE 7.0, but hardly an expert.

1. Capture footage from the HV20 using HDVsplit (google for download) which will capture and break up/log your clips based on scene detection. If you just capture a series of clips in one large capture the pull down removal will not work correctly.

2. Set up a 23.976 fps composition in AE with 1400x1080 HDV, 1.33 par, full resolution, with "lock 4:3 aspect unchecked.

3. Import your HDVsplit captured clips into AE and right click on each to interpret footage. Click on the "Guess 3:2 pulldown" button and accept what it comes up with. The sequence will change from clip to clip.

4. Copy the blank comp you created, and then use CTRL-V to paste as many comps as you have clips. Drag a clip into each comp...you may need to change lengths etc.

5. Now select each comp and hit CTRL-M to "Make Movie" . All of your clips will then be queued so you can click "Render" and walk away. You'll end with a collection of large avi files with pulldown removed.

6. Import these into your NLE with a 24fps preset and you're set.

It's hardly efficient, but once the clips are queued, you can just let them render overnight etc.

Cinetastic

04-13-2007, 06:00 AM

With lens capped, in CINE exposure mode, and 24P, I stepped through the range of exposure options. The exposure dial goes from +3 to -11.

+3: 1/8 f/1.8 10.5dB?
+2: 1/15 f/1.8 10.5dB?
+1: 1/15 f/1.8 9dB
+0: 1/24 f/1.8 9dB

Thanks (again) to Barry who lets me guess/feel what the Night exposure may actually be doing. I have used the auto exposure at Night (shooting everything in Cine Gamma mode/24p) and am very pleased with the results, but wouldn`t like less than 1/24 shutter to avoid any streaking echo too much. I have tried adding the exposure +1 - +6 and what Barry found is what I felt was happenning to the shutter (and I felt I did not like the look in the LCD), so I have been setting an exposure to a Night exterior key light and locking it at `0` and not adjusting.

With Barry`s daylight exposure table I was wondering if it would be wisest to add the Canon ND filter I bought on those brightest sunny Days to keep the HV20 at its happiest (and my fave 1/48)?

In
+0: 1/48 f/5.6 0dB
-1: 1/48 f/5.6 0dB
-2: 1/48 f/5.6 0dB
-3: 1/48 f/6.7 0dB
-4: 1/48 f/6.7 0dB
-5: 1/48 f/8.0 0dB
-6: 1/60 f/8.0 0dB
-7: 1/75 f/8.0 0dB
-8: 1/90 f/8.0 0dB
-9: 1/100 f/8.0 0dB
-10: 1/120 f/8.0 0dB
-11: 1/150 f/8.0 0dB

Verko

04-14-2007, 05:47 PM

Someone's probably suggested this already, but this thread is getting too long to read all the way through.

Can somebody hack this camera to have the gain turned off, somebody like Reel Stream? I would gladly pay to have this camera modified to act properly. I would even leave it with gain permanently turned off if that made the modification easier or cheaper.

Maybe Canon will make the next generation act properly, but I wouldn't expect to see that camera for another year. The HV20 is great in so many other ways.

Of course a 24PA mode would also be nice. As it is, I bring all my clips into FCP with the Intermediate codec, throw them onto a timeline, align them so that they all are in sequence together with the same 3:2 pulldown sequence, export that (not self-contained so it's fast), then do ONE reverse pulldown in Cinema Tools. It's much faster than figuring out the timing of each clip and doing them separately in Cinema Tools. If I'm going to be mixing HV20 with HVX200, I'll convert the first pre-removal sequence to DVCPRO-HD with Nattress' color smoother (to help out the 4:2:0) first, and then reverse pulldown.

Love the HV20's image (for the price and size), need mo' control!

vidled

04-14-2007, 06:01 PM

Maybe Canon will make the next generation act properly...

Canon is making the HV20 act properly already; just not the way YOU want it to!
:happy:

Verko

04-14-2007, 06:29 PM

Canon is making the HV20 act properly already; just not the way YOU want it to!
:happy:

Hehehehe. I ALONE define what is proper and what is not! Didn't you get the memo? Enough of this, I'm late for my MA (Megalomaniacs Anonymous) meeting!

(just kidding)

Seriously, does anyone on this forum WANT the inability to control gain, shutter, and aperture independently and yes, properly? You can always have your automatic mode, if that's what you want. That shouldn't preclude real manual control. It's just software, dammit! The whole idea of the HV20 was to improve on the HV10. It's the same sensor, just new ergos and "manual control" capability.

In any case, I'll use it as best I can, as with any tool, but I think the HV20 is good enough to warrant some hot-rodding. Even as is, the HV20 is working well with my HVX200, and later this summer I'll add Red to the mix.

I've been using the HVX for my personal needs the last year, so the HV20 is starting to make a very nice replacement for family stuff!

Barry_Green

04-14-2007, 09:52 PM

We'd all want that, but I don't know that the HV20 is going to be the one. It does what it does. Maybe they'll make an HV30 which adds the few missing controls that we'd all really want? I'd much rather have a factory original with a warranty and everything, rather than hacking it.

Jay Rodriguez

04-14-2007, 10:07 PM

or maybe if anyone wants those controls they should buy the A1. If they give you everything then what's the point of selling a camera that costs 2,500 more, is larger and heavier and named the A1?

Verko

04-15-2007, 12:39 AM

??????

Hey, can't hurt to dream. Still, I'm a little surprised at some of these recent comments.

What makes the Reel Stream such a good idea, but the idea of ripping into a $1000 camera so unacceptable? Strange.

Anyway, who cares. Use it for what it's good for, as is. But if I was a little more code savvy . . . . I'm not, so that's that.

Time to hit the sack, gotta get up for the early flight to NAB.

Verko

04-15-2007, 12:41 AM

P.S. The A1 is three-chip, whole different animal, don't ya think?

Jay Stebbins

04-16-2007, 07:33 PM

Barry,
if you put a light meter to your cell phone with the appropriate screen, would that be a starting point in creating a lighted lenscap to set the exposure baseline?

Thanks for your and everyone else's effort in this endeavor,
Jay

Barry_Green

04-16-2007, 09:57 PM

Probably. I'm using it as a consistent light generating scheme, and in context with the HV20 it's a rather enjoyable DIY type of solution...

Jake Danilchik

04-19-2007, 01:25 AM

on page 37 of the manual there is a A.SL Shutter adjustment/setting. This can be turned off to disallow "HAL" from adjusting the shutter speed in low light situations. Has anybody explored turning A.SL Shutter off in the menus ?

Norbert

04-21-2007, 10:36 AM

I was thinking...
You say we can not know when this camera adds gain to the picture, but what if you set the camera in Tv mode, lock the exposure and dial it up while looking at the iris through the lens. When the iris comes to a point where it doesn't open up any further, then all it does after that is adding gain because the shutter is already locked. Am I right?

Barry_Green

04-21-2007, 11:10 AM

Yes.

Norbert

04-21-2007, 11:36 AM

Cool, then it should be fairly easy to stay away from the gain. Or can it add gain even if the iris isn't fully opened?

Barry_Green

04-21-2007, 01:20 PM

It doesn't appear to add gain when the iris is not fully open.

Jay Stebbins

04-23-2007, 10:16 PM

I finally had some time to play with my HV-20. I used Barry's cell phone white screen to set a baseline as described earlier in this post. Now Barry's chart will likely be different that a chart I would derive using my phone as a baseline. Odds are we have different phones.

But I did notice one thing. I pulled the Mini SD chip out of my phone a stuck in in my camera. You can take a picture while filming, and the Aperture flashes in the lower right corner of the screen. (I am shooting in TV mode so I already know my shutter speed) This if nothing else is a great way to find out what your camera is doing. (you might have to change a n option or two in the camera settings to get the camera to do this, I don't remember)

If you set your baseline with a phone or whatever you choose to use, you can then take a picture for every exposure setting. (-11---0---+11). When you view your pictures in play mode from the sd card it will show a histogram and the information for each exposure adjustment. You do need to be organized because is doesn't exactly tell you +11, it has some other type of metric system.

Although Gain is not displayed. However, when you get to the wide end of the lens, (F/1.8) the first time you see that particular F-stop there should not be any gain. The second time, there should be some, the time after that more. How much I have no idea. Where the brightness of your baseline falls in the spectrum will dictate how many times you see this end repetitively.

On the long end of the lens (F5.6 or higher?) when the f/stop begins to repeat you can assume the ND filters will have engaged.

THis is what I learned this weekend.
Oh yeah, the OIS likes to be turned off on the tripod. And removing the pull down is time consuming.

Have fun,
Jay

Robert Robinson

04-24-2007, 07:47 AM

Hello (noob here),

Based on what I've read in this thread (thanks Barry for your amazing hours of effort!), if I use a 35mm adapter (I own a Brevis and love it) then would this work?

1) TV Mode (shutter priority) set to 1/48
2) Dial in the aperture neccessary on the mounted lens on the adapter for DOF
3) Take a photo on the HV20
4) Check the aperture display (the histogram is just a bonus!)
5) If the aperture is greater than 1.8 (seems it usually is) then there must be ZERO gain?
6) EDIT: If it's not then use EXP and adjust and repreat steps 3-5 until it is...

This seems like a comfortable solution considering that there is a constant shutter speed and ZERO gain. The iris on the camera is not that important (as long as its greater than 1.8) since the aperture on the mounted lens on the adapter is what is really being used to dial in the exposure (and DOF).

Am I missing anything here?

EDIT: I did notice that when using PHOTO that the shutter falls back to 1/30 (there is no 1/48 setting?), but thats alright since we're really just looking for what the aperture is set to and 1/30 is slower than 1/48 so if the aperture is "fine" at 1/30 it will also be fine at 1/48.

Thanks!

Rob Robinson

Jay Stebbins

04-24-2007, 08:39 AM

Hey Rob,

I am not much more than a noob, but yes you have it. Once the camera is set. You would use The Aperture on your 35mm lens, in combination with filters or lights (subtracting or adding light) to balance your picture. At that point you will be taking advantage of the Zebra stripe functions of the camera.

If you are shooting faces you would use the 70 zebra setting and pay attention to the highlights on your subjects face. If you are shooting general scenes then the 100 setting would suit you. Use the filters, 35mm aperture in order to get the zebras to just show.

This should get you a good picture to work with in post.

I am in the middle of John Jackman's "lighting for digital video and television". It has been a very good read so far.

* Warning---- I am 3/4 through the book, there might be something on the last page that shoots this all to hell......

Have fun,
Jay

Edit, yes it seems to get you there, as long as we are careful at 1.8 we should be fine. Besides, most lens do not seem to be at their best wide open anyhow.

Robert Robinson

04-24-2007, 08:43 AM

I am in the middle of John Jackman's "lighting for digital video and television". It has been a very good read so far.

* Warning---- I am 3/4 through the book, there might be something on the last page that shoots this all to hell......

Thanks Jay,

Yes that book was AWESOME. I read it in one read (whew) but need to go back again and take some notes now. Looking forward to some greats shots with the HV20 and Brevis. Seems like a match made in (affordable) heaven.

Thanks!

Rob Robinson

Norbert

04-24-2007, 02:46 PM

This seems like a comfortable solution considering that there is a constant shutter speed and ZERO gain. The iris on the camera is not that important (as long as its greater than 1.8) since the aperture on the mounted lens on the adapter is what is really being used to dial in the exposure (and DOF).If you don't have a miniSD card you could also look at the iris through the lens of the HV20. When it doesn't open up anymore it starts adding gain instead (if your shutterspeed is locked). I think Barry mentioned earlier in this thread that it would not be a good idea to use the iris on the 35mm lens if you want to step down below F4.0 to get a proper exposure. Apparently that's where you start seeing the grain on the ground glass of the adapter.

Robert Robinson

04-24-2007, 03:43 PM

If you don't have a miniSD card you could also look at the iris through the lens of the HV20. When it doesn't open up anymore it starts adding gain instead (if your shutterspeed is locked). I think Barry mentioned earlier in this thread that it would not be a good idea to use the iris on the 35mm lens if you want to step down below F4.0 to get a proper exposure. Apparently that's where you start seeing the grain on the ground glass of the adapter.

Good point (about just looking at the iris) except that with the 35mm adapter connected its more difficult to do (would have to remove it first). Taking the PHOTO is also not all that convenient but hey its all about the least amount of painful work around I guess. Also, from my experience with the Brevis (and certain faster lenses) you can actually go past F4.0 and still be fine (as far as no visible grain).

Jay Stebbins

04-24-2007, 07:48 PM

Actually, taking a photo while shooting is very easy. You just hold down the photo button next to the zoom toggle while you are in video mode. The aperture will show up briefly in the lower right corner. If you want to see the histogram, then you need to switch over to view the card.

It is better than nothing. I just wish we could turn off the gain like the Everio....

Jay

Robert Robinson

04-24-2007, 07:53 PM

Actually, taking a photo while shooting is very easy. You just hold down the photo button next to the zoom toggle while you are in video mode. The aperture will show up briefly in the lower right corner. If you want to see the histogram, then you need to switch over to view the card.

Jay

Jay, I just tried that - I get a little red box in the lower left that says [Off] instead. Is there a setting I need to turn on?

EDIT: Just found it - "Still Image Set" - Cool! That makes it sooooo much easier!

Thanks!

Rob Robinson

Robert Robinson

04-24-2007, 08:26 PM

Interesting... When using PHOTO in video mode (thanks Jay!) you see the aperture (or is it? - read on) and the shutter speed (if you press the PHOTO button down halfway). What is interesting is that the lowest reading is F2.2 (lens cap on) and then it increments by .2 as you add more light (i.e. 2.2, 2.4, 2.6, 2.8 etc...). This must be the addition of gain between stops I would imagine? (1/3 increments) So, in order for the ZERO gain trick to work we'll need to stay clear of the bottom (2.2) and look for something like 2.4 I would think? Although, I caught it reading 3.6 which the is the next few stops down (3.4) plus presumably some gain!? Oh no! So is the answer to make sure that the reading is EXACTLY the stop intervals? (1.8, 2.0, 2.4, 2.8, 3.4, 4.0, 4.8, 5.6, 6.7, 8.0 as per the manual page 47). The assumption being is that the display is yielding actual EXPOSURE readouts (not just the iris ). So as long as the figure is one of the iris settings (with no added gain increments) then we're OK? I think this PHOTO trick may be giving us just the info we need!

EDIT: Now that I think about it, 2.2 (with lens cap on) must be almost wide open iris (2.0) plus an increment of gain (2.0 + .2 = 2.2). Makes sense now. So 2.2 is bad, very bad... 2.4 on the other hand sounds like ZERO gain to me!

EDIT: FOLKS WE MAY HAVE IT! I was able to lock in the shutter at 1/48 and the EXPOSURE (iris + ZERO gain) at 2.4 (can't get to less than 2.4 it seems) and then I had total exposure control with the brevis 35mm adapter. SWEET!!!!

EDIT: For those without a 35mm adapter (not to leave anyone out here), you can still adjust the EXP bar and then see what the actual EXPOSURE is with the PHOTO method (above), then lock it in (by leeaving the EXP bar displayed). Again, in order to have ZERO gain, my conjecture is that the readout needs to be an interval of 2.4, 2.8, 3.4, etc.. (The list of available apertues on page 47)

EDIT: I have the term "Gain" confused with ND filters in this post - duh!

Thanks!

Rob Robinson

Barry_Green

04-24-2007, 09:15 PM

Robert Robinson

04-24-2007, 09:26 PM

No, 2.2 and 2.4 won't represent gain at all. 2.4 is a 1/2-stop marking between 2.0 and 2.8, so 2.2 and 2.6 are 1/4-stop settings. Either way they should be at zero gain.

You'll only have gain creeping in if you open up wider than the maximum; even so the iris should still show maximum. The increments you're seeing are not gain. The HV20 won't tell you what gain it's at, at all, near as I can tell.

Barry (in my most humbled voice),

Aha! I may have it backwards (told you I was a noobe). I may have gain and ND filters reversed in my thinking. So to go from 2.0 to 2.2 that is not GAIN being added, but likely an ND filter? Gain is added when going the other direction (from 3.8 to 3.6 lets say). Ok, to restate what the GOAL is then: We want ZERO gain and NO ND filters perhaps? Does my original conjecture still stand though? That as long as the EXPOSURE reading (via PHOTO) is an interval of the actual aperture values then we can be assured that no gain or filters have been added? I mean why would they is the iris has taken care of it first?

Thanks!

Rob Robinson

Barry_Green

04-24-2007, 09:30 PM

No, 2.0 to 2.2 to 2.4 to 2.8 ... all the way down to 8.0 and 9.5 and 11, etc, are all indications that the iris is getting smaller.

The goal is zero gain, with a 1/48 shutter; whether there are filters present or not. And that's the one thing the HV20 doesn't tell you, is the amount of gain it's adding. However, presumably if it's smaller than maximum wide open (and that number changes depending on what zoom position you're at!) there should be no gain.

So as long as it's not wide open, there's probably no gain being added.

Robert Robinson

04-24-2007, 09:33 PM

So as long as it's not wide open, there's probably no gain being added.

I got ya now. So, since 2.4 is not wide-open then like you say "probably no gain being added". Works for me!

Thanks!

Rob Robinson

Jay Stebbins

04-24-2007, 10:19 PM

Hey Robert,

Wide open is f/1.8... At 1.8 the iris is wide open to let in the light, just like your eyes. If the camera had started to show f/stops like 1.1 or .7 then your theory on gain compensated aperture readings would have been right. The more wide the aperture the more shallow the depth of field will be as well. When the hv-20 can't open the aperture any further to let in more light, it starts adding gain. It is like using a faster film (higher ISO) in a camera. The higher the ISO or gain, the more grain is introduced to your picture.

When you stop down a lens, make the iris smaller, let in less light, like your eye does when you step outside, the f/stop number goes higher (f/11-f/20?). When the aperture gets as small as possible the HV-20 slides Neutral Density filters in place to keep the picture from becoming over exposed. The more you stop down a camera the wider the depth of field becomes.

The various scene settings will change when gain is added, ND filters are engaged, shutter speed limited. Slowly through people experimenting and sharing, maybe we can figure out what this camera is doing.

I hope this helps put a little more of this in perspective.

Good luck,
Jay

Barry_Green

04-24-2007, 10:28 PM

It's 1.8 at wide angle, but when you zoom in then it becomes more like 2.8 or so. (I don't have it in front of me so can't verify right away). But the point is, it's not a constant 1.8; it depends on your zoom setting.

Robert Robinson

04-25-2007, 04:48 AM

Hey Robert,

I hope this helps put a little more of this in perspective.

Jay
Jay,

Thanks, that does help clear some things up for me. Especially the part about the ND filters not being added until the iris is the smallest (didnt know that). On my post I really had gain and filter backwards (long day). I do know the difference, but its just hard to keep them straight when referring to the exposure settings, etc...

Barry,

Your point about the zoom setting makes total sense to me know. Thats why I can't see 1.8 with the lens cap on (as I would have expected). I'll have to check what zoom I had it on when I read 2.2 as the bottom in my example.

So, my next question is that what are those .2 increments all about? If they are not gain (since we're in the middle of the iris range) and they are not ND filters then what are they? Is it possible for the HV20 to do 1/2 and 1/4 stops (physically?) So, unlike a real lens you can have partial stop movements?

If that's the case then perhaps the "new" plan of attack would be to put the lens cap on (to get the iris opened up as much as possible) then depending on your zoom settings you would see an APERTURE readout (not compensated exposure as I originally thought) by using PHOTO and the EXP bar readout for +0. Then increase the EXP bar until you see it add at LEAST one .2 increment (i.e. from 2.2 to 2.4). Then you'd know that you are now free from any GAIN (and now I've learned free of any ND filters as well). Then either leave it there (I think I will) or perhaps then move it back one EXP "notch" to have the iris as wide-open as possible with the hope that you're still free from gain (two notches and you'd be asking for trouble for sure)?

Wow, this stuff is tricky! Thanks to you both for having patience with me as we figure this out. I very much want this "little cam that could" to work out!

Thanks!

Rob Robinson

Robert Robinson

04-25-2007, 06:00 AM

Ok, tried a few things...

First, my zoom setting is about 1/3 zoomed in (in order to frame the GC in the Brevis 35mm adapter perfectly). As Barry points out that affects what the lowest iris setting can be (the range is in fact from 1.8 (wide) to 2.8(full zoom) ).

After knowing my "bottom" was 2.2 (for my given zoom), I then looked at what EXP adjustments I could make. Well, with the lens cap on you can't increase (only decrease from +0 to -11). Makes sense since one would expect the cam to try to add MAX gain with total darkness (lens cap on). So I figured that using the lens cap alone won't do the trick (since I can't get the aperture to move off from 2.2 I can't reliable say for sure that I've removed all the gain it was adding).

So, instead I tried this. I took the lens cap off, the then pointed the cam so that I registered anything greater than my bottom of 2.2 (although staying as close to 2.2 as possible). As an example, I read F3.4 on the cam (again using PHOTO - love that BTW), then set the EXP bar to +0 to "lock it in". Then with each successive movement of the EXP bar (increasing) the APERTURE reading went from 3.4 to 3.2, 2.8, 2.6, 2.4, and finally back to 2.2 (which was +5 on the EXP bar). Then for the final test, I kept going (to +6 through +11) and as expected the APERTURE didnt budge (stayed at 2.2), BUT you could see GAIN being adding to the picture (again as expected when the iris is "wide-open"). I then put the EXP bar back to +5 (which is 2.2) and I think I am fairly confident now that a) I have the iris as wide open as possible (given the zoom setting) and that I have ZERO gain added by the camera!

EDIT: So the take home here is that you first need to "find your bottom" that is dependent on your zoom setting by using a lens cap (total darkness).

Are we there yet?

Thanks!

Rob Robinson

AuditoryVisuals

04-25-2007, 06:32 AM

Norbert

04-25-2007, 06:53 AM

Robert Robinson

04-25-2007, 07:10 AM

Robert, all that makes perfect sense to me. Stupid question maybe, but do you need a miniSD card in the camera to use the PHOTO button trick? I can't get it to work in camera mode and I'm starting to think it's because I don't have a card.

Yes, you do need a card (although by pressing the PHOTO button down only half way you never really take a picture - and thus fill up the card with junk). You also need to set "Still I Rec." to ON in the menu.

Robert Robinson

04-25-2007, 07:13 AM

http://www.dvxuser.com/V6/showpost.php?p=913187&postcount=80

Would this be the answer?

With the lens cap on I verified that the available aperture range is only 1.8 to 2.8 from wide (no zoom) to telephoto (full zoom).

What are those readings from? EDIT: Nevermind I see your earlier posts.

Robert Robinson

04-25-2007, 03:31 PM

I took some inside and outside shots today and tried out the new technique. I'm happy to say that it is a very workable solution (for me at least). One other thing that helped was to turn OFF the BEEP so that when pressing the PHOTO button halfway (which you end up doing a lot to verify the aperture) it doesn't get annoying. I can now within a few seconds of framing the shot press EXP, dial in my "bottom" setting of 2.2 (based on the zoom setting), and then lock it it in for the duration of the shot knowing that BOTH shutter speed and aperture are now FIXED and that there is no GAIN being added to the shot.

Now, I'm experimenting with good combinations of using the lens aperture on the Brevis 35mm adapter and HV20 aperture as both in combination equals the ultimate exposure. On the one extreme I'd like to only use the 35mm adapter (and thereby maximize my DOF) but at some point the grain from the GC (from the adapter) interferes so I may need to increase the aperture on the HV20 (which I can now do reliably using the EXP bar and PHOTO buttons). Bummer of course is that whatever settings I used on the 35 adapter won't be recorded on the tape (for playback reference). So, my latest thought is to FIRST decide what DOF I'm interested in, set the 35 adapter aperture accordingly and then set the aperture on the HV20 in order to set the final exposure (checking zebras, etc...) What's handy is that when you turn EXP off the HV20 tries to find "optimal" exposure for you anyway and its a good place to start from when then going back and manually adjusting the final desired aperture setting .

EDIT: For reference the complete sequence:

1) TV mode (shutter priority) - Set shutter to desired speed (1/48 for 24p)
2) Set "Still Image Rec" to ON - in order use the PHOTO button in video mode (you'll also need a mini-sd card in the cam)
3) Frame the shot (set zoom)
4) Put lens cap on
5) Press the PHOTO button down halfway - this will display current aperture and shutter
6) Note what the aperture setting is. It will be between 1.8 and 2.8 depending on the amount of zoom. Lets call this the "bottom" iris setting.
7) Take lens cap back off and re-frame shot
8) Select EXP bar (with joystick)
9) Press PHOTO button down halfway and note aperture
10) While moving EXP bar (increase or decrease) also press PHOTO button halfway to select the desired aperture
11) Note that once the aperture is at the "bottom" iris setting as noted in step 6 then any more movements of the EXP bar will introduce gain (so dont go past this if you want ZERO gain)
12) Press joystick again to leave just the EXP bar displayed so that the exposure is now FIXED.
13) Record footage! - knowing that shutter, aperture, and gain are all under your control!

Jay Stebbins

04-25-2007, 04:57 PM

Nice job Robert,

Now here is the last piece to your puzzle.... http://www.kenrockwell.com/tech/filters.htm

Robert Robinson

04-25-2007, 05:02 PM

Thanks Jay (your encouragement concerning using the PHOTO button really paid off).

Yes, Filters, Filters, Filters... How did you know that was next on my list?

I have the Brevis rails and Mattebox so I'm all set to start using some ND filters. What do you suggest? Is it better to add filters or let the HV20 decrease the iris? Since I'm using a 35mm adapter I don't lose DOF when the HV20 compensates for the exposure.

Thanks!

Rob Robinson

Jay Stebbins

04-25-2007, 05:20 PM

after you read that article you will be stoked to get some nice filters. Solid ND and some graduated ND for landscape shots. http://www.singh-ray.com/grndgrads.html

Singh-ray makes some really nice filters, expensive but nice.

Look at the Cokin "P"system, the filters are not overly expensive and they are fantastic. You can spend a lot more on filters, but for now, why?, start here.

Read the Ken Rockwell article is is very informative. He also has great reviews on the old Nikon lenses.

In a studio they shape the picture by carefully "adding lights". Outside you can create your picture by carefully "subtracting light" & playing the angles... The trick is speed, as the perfect moment is usually fleeting.

Set the HV-20 & Brevis and use some filters to balance the exposure.

Good Luck,
Jay

gmmllc

07-30-2007, 08:07 PM

These solutions are brilliant. I am not that creative at workarounds, but decided to by the HV20 after reading them. Thanks for saving me $2500 on an XH-A1.

I've found that covering the lens with a lighted screen (I tried my PDA with a white JPEG) forced the aperture to close too much for most indoor scenes , even well-lit ones, when I locked exposure. Then I did not have enough range in the exposure settings to get down to where I wanted. For example, forcing exposure to lock at f8 does not help when the scence is really a 1.8-2.4.

Also, I think you really want the camera to set itself relative to your scene somewhat and then adjust up/down from there. Just make sure you have an SD card installed to check f-stop or shutter as you adjust so you are relatively sure there is no gain or ND filter.

I have two ideas on a solution:

First: Since white will be about the brightest area of the scene, I've used a whiteboard (a $10 dry erase board that I also use for white balance) to lock exposure. Assuming the hypotheses in these forums regarding gain are correct, that should get you about as far from gain as possible with your scene.

If memory serves, here's the sequence:

Light the scene
Press Func
Set Tv mode
Zoom in on white board and set white balance manually
Press Func to exit
Set shutter to 1/48 (or whatever you want, I shoot in 24p) with joystick
Focus (I often zoom in on the subject, let it auto focus and lock it there by switching to manual focus)
Put your whiteboard in a brightly-lit area of the scene
Zoom in on the whiteboard again
Press joystick
Scroll to exposure
Lock exposure
Remove white board
Zoom out and visually adjust exposure.Here is an example using that method from a lighting test:
http://i193.photobucket.com/albums/z205/gotlerTech/mpeg/color-wmp.jpg

Ok, so I should have shaved.

A different idea: I have not tried this yet, but instead of locking exposure to the white board, you could use the camera as a light meter. Like the focusing method:

Zoom in on the subject (or the critical lighting area)
Lock/adjust exposure there (maybe determine an acceptable exposure range).
Zoom out and adjust exposure for the scene within the acceptable range.

Mark Dog

07-31-2007, 02:25 AM

can yo upost the video of that of what you did gmmlic and show us the moving footage

Ian-T

08-01-2007, 06:32 PM

gmllc....that is a very clean picture...no noise at all. What was your lighting situation like in that room (I see a lamp behind you)?

gmmllc

08-01-2007, 07:38 PM

Thanks for the feedback.

I'm re-learning all of this in the digital world. I was a film major for a short time in college in the 80's. I actually used to splice film with tape and glue. Heh heh. I don't miss that. Lighting, FX and animation were my areas of interest. I do miss the look and cadence of film, which is why I chose the HV20. Didn't have the budget for the XH-A1.

Anyway, the ambient lighting includes 6-60watt recessed can lights in the ceiling. They don't provide much light as they are mostly aimed at the walls, but help a bit. The lamp behind me has I think a 60W bulb with 3 lower-watt candle bulbs.

I lit myself and the piano with a 3-point setup. I have the KT-900 kit from Smith Victor
http://www.smithvictor.com/products/detail.asp?prodid=435

I have the incandescent version (the others were not available when I bought it).

Anyway, looking at it from the camera's point of view, here is the setup:

500W key light about 5-6 feet high and about 30 degrees to the left, shot through a white umbrella. The key is pointed about half way between my face and the piano.
250W (might have been 150W) fill light about 4 feet high and about 45 degrees to the right, also shot through a white umbrella
250W (also might have been 150W) on a boom to the left about 45-60 degrees from the camera with the narrow reflector aimed directly into the piano. It is just out of the shot and is far enough back to also provide some hair/shoulder lighting. That was the trick. The third light had to light the interior and my shoulders. This is the setup that I will have to contend with on location.The only thing I don't like is how dark the wall is behind me and to the right. Given the limitation of 3 lights, I had to trade that off for a better lit interior of the piano.

The camera settings are 24P, Shutter priority (Tv) at 1/48 and either I think a 2.4 f-stop.

I hope that helps.