Quote:
Originally Posted by sk66
I say "apparent exposure" because "what" was recorded (the exposure) does not change, but who really cares about that? We care about how it is presented and that does change..
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This is the one. It turns out whether white balance affects expsoure is all down to semantics.
What it does affect is the brightness of the final output. (RAW is not an output)
You can see the effect very clearly for your self. Take a RAW file that contains a scene the fills the cameras dynamic range (blown shadows and highlights) and in the RAW converter turn on the blinkies that highlight the blown pixels. Now move the WB slider to different settings and you will see the number of blown pixels change. Presumably this is because as you change the colour balance you are effectivly adjusting the brightness of the different RGB channels. This will cause different pixels to blow out.
So what does this mean in real life when shooting.
For me nothing: Since I shoot all shots in RAW and Auto WB I can be confident that my white balance is in the ball park. Therefore when I set the correct WB in post I'm only changing by small amounts, if this does cause some extra pixels to blow it is well within the latitude afforded by my 12 bit files.
If I shot JPEG then it may be more of an issue but there are so many other reasons I would need to pay more attention to WB before shooting that this pales into insignificance.
The only thing I can see this being important for is RAW conversion work flow. WB should be the first thing you change since it affects the brightness of the picture, if you made all of your other edits and then changed the WB it would affect everthing you had done before.