Noise in blue.

armisiano

armisiano

Veteran
This is something that's always bugged me, so I have to ask. WHY is there so much noise in blue? If I'm shooting something, espeacially if it's a little dim, not even dark, just dim, if there's any blue light or blue colors, it is FILLED HEAVILY with video noise. I always have to adjust it when shooting so that doesn't happen and then try to "blue it up" in post.

Why is this?
 
Actually, it's because CCD and CMOS sensors have a lower response to blue than red and green. The blue channel needs to be boosted more electronically, leading to more noise.

This happens in everything from 1 CCD consumer cameras to 3 CCD or CMOS professional HD cameras, regardless of color sampling.

You'll get the cleanest image if you light everything with daylight-balanced sources. If you use Tungsten lights, they are very deficient in blue, so when you white balance to correct for it, you are boosting the blue channel even more, making it much noisier.
 
So if I have my white balance set to 32k the footage will be noisier than if it were set to say 56k? Yes?
 
armisiano said:
So if I have my white balance set to 32k the footage will be noisier than if it were set to say 56k? Yes?
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No. Your white balance will just be wrong and your blues will still be noisy. You need to use lighting that actually has more blue in it which will FORCE you to change the white balance of the camera.

Think of it this way. Your camera is having to invent blue because tungsten light has so little of it. If you use light that has more blue in it, your camera isn't trying to invent blue, and the blue channel is less noisy.
 
New question, slightly different direction:

Taking the above information into account, I'm shooting something, and the colors look best by far when I set my white balance to 32k. The problem? Video noise gets amp'd up. In your experiences, will I still yield good results if I shoot it with a warmer white balance (less noise) and just color correct it in post?
 
No, that'll make it worse, because you're then trying to bring up blue in the image when there's very, very little there. I'm sure you've tried to brighten dark footage in post and ended up with a noisy picture? You'll be doing the same thing with the blue.
 
David Jimerson said:
No, that'll make it worse, because you're then trying to bring up blue in the image when there's very, very little there. I'm sure you've tried to brighten dark footage in post and ended up with a noisy picture? You'll be doing the same thing with the blue.
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So at this point it's best (since my lighting design won't be changing) to just white balance it the way I want (in this case 32k) and cope with the little bit of video noise that'll be there.
 
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