HV20 gain

rapsucks said:
I guess the real test would be to see some footage in different situations--with the settings recorded, if possible.
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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?
 
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.
 
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...
 
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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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.
 
jenningsp said:
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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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.
 
rawfa said:
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.
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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.
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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.
 
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.
 
Barry_Green said:
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.
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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 :)
 
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!
 
jenningsp said:
and the HV20 manual.
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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.
 
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?
 
jenningsp said:
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
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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?
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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.
 
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.
 
Barry_Green said:
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.
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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.
 
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.
 
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?
 
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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The Megaton bomb that, depending on the answer, either caused the HV20's popularity to continue to spike, or ended that topic altogether, and prompted a lot of angry calls to Canon. Still, not a bad price for a deck though.
 
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