Quote:
Originally Posted by fletch
So what do you think? Is it?
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It depends on what you mean by "exposure" and on what you mean by "white balance".
Technically, "exposure" is the process of exposing the film/sensor to the image. It consists of an aperture setting and a shutter speed setting. f/4 is f/4 regardless of white balance or anything else. 1/200 is 1/200 regardless of white balance or anything else.
Some people use the word "exposure" to mean "in-camera metering". On DSLRs, in-camera metering is not affected by the in-camera white balance setting as it is picked up by separate metering sensors. (I don't know if maybe some of the new-generation live-view DSLRs can do metering from the sensor image, in which case white balance might be involved.)
However, if you use the word "white balance" to mean the color of the lighting then there can be a small effect on in-camera metering. Nikon uses full-color metering sensors, while Canon uses monochrome "silicon blue cells" that generally do a pretty good job of providing even response across the visible light spectrum. I can't speak for other camera brands. The camera makers try to keep the in-camera metering from being affected by the color of the scene/lighting, but perfection eludes them.
Some people use the word "exposure" to mean "desired brightness in the JPEG result". In this case the white balance process could conceivably shift the overall JPEG image brightness, depending on the color of the lighting, the colors in the scene, and the selection of white balance adjustment. In practice, the white balance adjustment is designed to have little effect for normal scenes. But again, perfection eludes us.
Some people use the in-camera histogram to determine if they need to adjust the exposure settings. In most cases, the in-camera white balance adjustment
does affect the in-camera histogram. That could cause the photographer to choose slightly different exposure settings for the same scene.
For some people, the desired exposure for Raw files is "as far to the right as possible". In-camera white balance is not applicable to Raw. The color of the lighting on the scene could affect how far to the right the photographer can safely expose, because the red, green, and blue sensor elements are not equally sensitive nor will they factor equally in the resulting image after Raw developing is done with a particular white balance setting.
So the overall answer is, "No, not really." There are a number of cases where there could be some minor differences depending on what you mean by "exposure" and by "white balance", but the differences are small enough to be ignored.