Gain, Gain-less, Negative Gain versus "Fixing it in Post"? at DVinfo.net

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Old August 19th, 2007, 01:09 AM   #1
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Gain, Gain-less, Negative Gain versus "Fixing it in Post"?

To get the best picture, camera gain should be set to zero.

Except light changes. E.g., I'm shooting B-Roll from out my car window. Lighting will change depending on the street I go down, trees providing intermittent shade, etc.

So if I lock gain, shutter and iris, then I'm stuck stuck being under and/or over exposed sometimes. (I guess the camera could have an automatic ND filter that could fix this problem, but I'm not sure.)

So the questions are:

1. How bad is it to allow the camer to add a little gain?

2. Should I set up with negative gain (negative gain seems pretty harmless, right?) and hope the camera never compensates so much that it goes into positive gain?

3. Do I just lock the exposure completely and "fix it in post?" My problem with fixing in post is that I come from a still photography film background and was taught "Do as much processing INSIDE the camera as you can." Is Sony Vegas or Avid Xpress Pro really going do a better job lighten my footage than the camera would by turning up the gain? At best, won't they essentially do the same thing?

Enough newbie rambling on my part, please FEEL FREE to answer any or all of these questions. Oh, BTW, the camera will be an HV-20, but the possibility exists to add an XH-A1 down the line.

THANKS MUCH as always.
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Old August 19th, 2007, 01:31 AM   #2
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How about you do a test?

A- Bracket multiple exposures.

Learn how your zebras look so that when you're shooting, you can figure out what exposure you're getting.

B- In post, play around with the footage to see what combination of exposure + color correction works best.

C- When you're shooting, it may be good to manually adjust the exposure on your camera.
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Old August 21st, 2007, 09:42 AM   #3
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Now you know why movies cost a lot to make

There is no substitute for painful, time consuming testing. You will have to drive down those streets and make notes of the best settings (using the zebras), then drive again and shoot again. If the Sun goes behind the clouds, start over... and over... and over...

Adding grain... depends on the camera. Sony HDV camcorders handle it better, most of us don't see much difference up until about +9dB; but this sounds like daylight shots, I don't see why you would bump it up.

Your still photo experience is valid in moving pictures too - leave to post as little as possible. Generally try underexposing slightly - that can be "fixed in post", while anything overexposed is lost for ever.
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Old August 21st, 2007, 04:59 PM   #4
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Ervin,

I will be doing what's been suggested above.

May I ask if there is an issue with using negative gain to get the desired exposure?

It seems that adjusting the gain downward is more finely adjustable than using a combination of built-in and external ND filters.


Thanks very much.
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Old August 22nd, 2007, 06:50 AM   #5
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I have no experience with negative gain as my camera does not offer that. You should be fine adjusting the iris.

As bad as it sounds, in constantly changing light conditions I've even tried leaving either the gain or the iris on auto with satisfactory results - you may want to experiment with that as well. In extreme situations it might look like footage shot with a $300 cheapo but if the change is not significant, it may look like you did it like a pro... manually. As I already said, there is no substitute for experimenting.
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