HV20 gain

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

Emanuel said:
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
Click to expand...

e-steve said:
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...
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jenningsp said:
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 :)
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rawfa said:
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".
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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.
 
Gordon Prince said:
Okay. But doesn't these posts help at all? You said no word on these tips.
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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.
 
Barry_Green said:
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
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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.

Gordon Prince said:
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?
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Barry_Green said:
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?
Click to expand...

Haven't you tried the Spotlight mode yet? It said at DVinfo it would set the gain to zero.
 
Barry_Green said:
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!
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Barry, where did you find the camera for $925? Lowest I found was $1069.
 
AuditoryVisuals said:
Haven't you tried the Spotlight mode yet? It said at DVinfo it would set the gain to zero.
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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 said:
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.
Click to expand...

the only way to find out is to do the tests.

put it in spotlight mode. cover the lens. push the exposure button. point it at a dark area. push record. check on a decent monitor if there is dancing grain in the blacks.

if there is grain, push the exposure down until you can't see any. if there isn't any, push the exposure up till you see some.

that's probably all you can do. it's not the most technical test, but if we get a bunch of people to try this and post there results, then we can have some grounding :)
 
Barry_Green said:
www.mediasupplystore.com, an authorized dealer.
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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.
 
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.
 
Barry_Green said:
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.
Click to expand...

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.
 
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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.
 
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.
 
:thumbup:

Barry_Green said:
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.
Click to expand...

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