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increasing gain setting in camera vs. pushing image on computer


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#1 Daniel Madsen

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Posted 24 September 2012 - 06:02 PM

Hello:

Is there any difference in image quality when you use gain while shooting vs. pushing the image/increasing image brightness in post?

Thanks,
Dan
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#2 Alessandro Machi

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Posted 24 September 2012 - 09:08 PM

My prior experience is that it's all in the lower black levels. if they are already crushed, you won't be able to do anything later on. Lift the blacks without clipping the highlights when shooting should give you the best options later on, however, then there is the trade off issue of shooting wide open versus maybe stopping down a stop for potentially a clearer image.

Also, make sure your lens is cleaned really well (no thumb prints), especially in back lit situations.
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#3 Jeremy Ables

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Posted 25 September 2012 - 05:37 PM

My experience is not so much a fix it in post mentality on this particular issue because everything built into the camera was done for a reason. You can push gain in camera if you deem it necessary or aesthetically pleasing once you look at the footage but I am afraid what you will find is that no matter where you push it you are going to end up with some kind of noise injected into the image. Better options depending on setup, equipment and look you are going for is to do what Alessandro said shoot with your lens on a wider aperture and if you have already done that find a way to add more light. The problem with shooting wide open is the difference in your depth of field and depending on equipment it may make little significance to a very large significance. Shoot it to look like you want it to look like first then worry about adding or taking away. Much safer.
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#4 Stuart Brereton

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Posted 26 September 2012 - 02:47 AM

Adding gain to the image in camera applies a uniform increase to the video signal. This means that at the same time as you are adding a little detail to your shadows, you could be clipping your highlights. Adding gain in post allows you much more flexibility and control, as even a simple 3 way color corrector offers varying amounts of gain for shadows, mids and highlights.
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#5 Rick Cook

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Posted 27 September 2012 - 06:46 PM

You cant create information by simply lifting the blacks in post. If there is little to no detail on the low end of the image coming from the camera, then you will most likely have that (or information that suffers greatly) if you attempt to simply boost a signal in post.

In my opinion, the noise added to an image in post looks worse then noise introduced by increasing the gain in camera.
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#6 Victor Nhat Nguyen

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Posted 04 October 2012 - 01:33 AM

I say if you have to, turn up the gain in camera, and then do noise reduction in post. Don't know why you wouldn't just turn on some lights.
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#7 Sam Eilertsen

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Posted 04 October 2012 - 09:12 AM

I think it depends to a large degree on the camera. ISO/gain in digital is a complicated topic and it is worth putting some time into understanding it. On a RED for example, ISO is entirely metadata and there is no difference between changing in camera or in post. This is because RED records in RAW and ISO setting is entirely digital gain, changing ISO changes nothing prior to A/D conversion. On the other hand ISO on a Canon DSLR is actually two different things: analog gain prior to A/D conversion is used to bring the camera to the so-called "base" ISO's of 100/200/400/etc. Then after A/D conversion a digital adjustment is applied to bring the image up or down 1/3 stops, for 160/320/640 it is pulled down 1/3 stop and for 125/250/500 it is pushed up one stop. This is why shooting at multiples of 160 gives you lower noise, but you lose 1/3 stop of highlight protection. The new Aaton Penelope Delta can change ISO with a unique adjustment in the shutter that does not affect noise at all.

In general, I think the best practice is to get as close to what you want for the final image as you can, and if anything to overexpose a little if you can do so without clipping highlights. This gives you the most possible information to work with in post. I don't think in-camera gain will ever produce MORE noise than doing so in post. The more compressed your recording format the more important it is to avoid underexposure and get as close as possible to the final image in-camera, on cameras that use heavy compression like H.264 or MPEG-2, underexposure may create serious compression artifacts that will show up in post when you try to bring it up.
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