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HVX200 inherent gamma curve? what about HD NORM?


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#1 Nadav Hekselman

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Posted 08 August 2007 - 03:03 AM

Nowadays I'm shooting a feature documentary using the HVX200. This is actually the second time I'm using it , the first was for a fiction short. (which is now in editing).

On the first short fiction I used CINELIKE D with variable color matrix (according to scene) which is my DVX100 favorite and I liked the results very much.

But now, shooting this documentary, I suddenly feel the CINELIKE D is not the right choice. Maybe because i cant use a field monitor any more, maybe because of the ever changing environments with only available light . The feeling i get from this setting is too flat and too low saturated and i feel much more comfortable shooting with HD NORM.

Its hard thinking about post when you shoot live documentary , using the camera LCD, and I want to enjoy what I'm shooting when I'm shooting it..maybe that is the reason i like HD NORM . its less flat and more punchy.

But What really bothers me when im using the HD NORM is the post issue. I know the best thing for post is to keep the material with as much information possible and its obvious that CINELIKE D is better choice for that than HD NORM since it flatness the gamma, lowering contrast , giving more to work later on post..

so my questions are :

1) what is the inherent gamma curve for this camera, what is the original signal it generates before manipulation ( if there is one )? is it HD NORM? and if so isn't it more logical to use that gamma because manipulating it actually ruins the signal?

and if that is also true than isn't it better to shoot using HD NORM and leave the rest for post rather than switching to other gamma and loosing information? because you can flatten gamma in post too in a much more fine tuned way, less harming the signal. ( about highlights, you can compress them using knee).


2) does any one used HD NORM at all and what do you think about it? how did it handle in post?
is it possible than to bring the HD NORM gamma back to CINELIKE D?

I don't know why i got confused all of a sudden, I was really sure about my setting all this time,
I would love some advice...

P.S. after some reading im attracted to use the CINELIKE V, which i understand flattens the gamma but not as harsh as the CINELIKE D.

Thanks

Nadav Hekselman
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#2 Michael Nash

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Posted 08 August 2007 - 05:39 PM

The inherent gamma curve is "UNWATCHABLE." :P All video cameras apply some kind of gamma correction to the signal coming off the chips, because what comes off the chips in no way resembles a normal looking tonal distribution. You just have to pick the gamma curve that gives you the look you want (including noise as well as contrast).

If you're shooting with the CINELIKE D curve you also need to select the CINELIKE color matrix, to compensate for the flatter-looking color saturation. This is what this matrix was designed for. From there, you can increase the color saturation further if you like.

You might like CINELIKE V as a compromise. It's basically the same as curve as "D," but it steepens the contrast through the midtones for a little more "snap," and less flat looking. But otherwise it has the same highlight/shadow/color characteristics as "D."

If you like the look of HD NORM, by all means go ahead and use it. But what I would do in your situation is pre-program a couple different scene files for different lighting situations. For high-contrast day exteriors it might be based on "Cinelike D," and for flatter interiors maybe start with "HD Norm" or "Cinelike V." Take the time to visually match the color saturation, detail enhancement, detail coring and such so that all the scene files match each other, except for the contrast rendering. And I say visually match the settings, because the actual numbers may need to be different between scene files to produce the same look.

Think of it like switching film stocks with the turn of a dial. I do it with Betacam/Digibeta/HD all the time. It really helps in documentary shooting in uncontrolled environements.
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#3 Nadav Hekselman

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Posted 09 August 2007 - 12:46 AM

Thank you Michael, this helps a lot.
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