Dealing with 7D Noise?

Started Jan 30, 2013 | Discussions thread
Ubiquity99
Regular MemberPosts: 138
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Re: Dealing with 7D Noise?
In reply to rwbaron, Feb 1, 2013

rwbaron wrote:

fpix wrote:

rwbaron wrote:
...
Very importantt - be sure to perform a custom white balance before shooting. Getting the white balance correct will go a long way toward minimizing noise in the final image.
I shoot with a 7D and 99% is in RAW.
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Bob

Bob, please don't mind, but this is not true. If one shoots RAW the WB has absolutely no influence on the image since in post you can set whatever WB you want. And this has no consequence on noise or image quality. Try it out and tell us what you have found. I do know that lots of proffessionals emphasize this topic. I had a debatte with a presenter of a webinar once and he could not provide a meaningfull answer to my question why one would need to set a precise custom WB when she/he shoots RAW. Ok, it was a Xrite webinar, they where selling colorimeters and color checkers, I could understand he could not give an answer right away :-). I also understand that it makes life easier in post if you have a photo with color checker inside the frame. But why one would need to set custom WB when shooting RAW?

By the way, in some sports halls indoor it may be absolutely impossible to set an adequate custom WB. You may do it before the race starts, but if you shoot during the race with short T (say 1/1000s) you may observe several images in a burst having completely "wrong" WB. Guess why?

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Cristi@fpix.ro

This issue has been discussed on these forums many times and I've taken the advice and experimented myself. I believe the reason is when shooting RAW with an improper WB you are shifting the RGB channel values which then have to be corrected in post. This is not ideal if one wants to minimize noise in the final output as you end up having to push some channels and others may have clipped.

Try a simple comparison by shooting under incandescent light at very high ISO such as 12,800. Do the first RAW file in AWB and then do a custom WB and shoot the same image again at the same EV. Now convert and process the AWB file to match the one with the custom WB and examine the noise quality. I've done this and demonstrated to myself that it's better to get the WB correct in camera whenever possible.

Yes, it is very difficult to get the WB correct under mixed lighting and a custom WB is probably not an option but when it is it's been my experience that it's worthwhile doing.

Bob

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I don't think you quite understand what is involved in RAW conversion. When shooting RAW, the only thing that using custom WB does is change the WB metadata in the RAW file. This metadata is then used by the RAW converter to set the WB at the time of conversion. The WB settings in the camera do not in any way change the image data in the RAW file. RAW files do not have a white balance or color space. They don't really have any color information at all until they're run through a demosiacing algorithm. 
If you're using a non-destructive editing program like Lightroom, setting the correct WB in camera only has the advantage of not having to change the WB in Lightroom. But it's a lot easier to change the WB in Lightroom than it is to do it in camera, so that isn't much of an advantage. This is especially true if you're using something like a X-rite Colorcheck Passport which can be used to create color profiles and set the WB very accurately. 
In conclusion, there is absolutely no reason to set a custom WB in camera when shooting RAW. This is clear if you understand what exactly a RAW file is and what is involved in RAW conversion.

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