

After reading the above post, I am still not clear on the part around exposure. Is it possible that selecting one white balance over the other can cause the exposure to be different? This answer from that question in particular brings that point up exactly: https://photo.stackexchange.com/a/3598/4892





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    This is what you are looking for: photo.stackexchange.com/questions/664/… – Please Read Profile Nov 14 '12 at 3:14
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    @MattGrum You are assuming that the monochromatic light meters are equally sensitive at all wavelengths of light. That is seldom the case. In fact, it turns out that RGB light meters are less affected by color differences than monochromatic light meters are. The mono meters tend to be more sensitive at one end of the spectrum or the other. – Michael C Jan 17 '17 at 22:34




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Whether it is ACTUALLY more complex depends on the camera manufacturer.




  • With DSLRs the exposure decision is made before the sensor collects any raw data. The raw data collected is of course affected by selected exposure. The WB decision in terms of metering is based on how the camera uses the WB setting selected by the user to calibrate/correct the reading from the exposure meter. Before RGB metering became more common, if the WB was set to "Auto" the camera would meter based on a setting of 5200 K. If any other WB setting was selected the camera would adjust the metering based on the known response of the meter to light centered on that particular temperature. – Michael C Jan 17 '17 at 22:48

Apart from minor differences in exposure that have been well covered by the other answers, there is at least one other possibility where trying to adjust the raw data captured using a specific color temperature and white balance might be more limited in post-processing than by using a "Custom WB" in-camera at the time the image is taken.

At least with the Canon cameras I use, taking a photo of a white object and using that photo as a basis for Custom WB allows a wider latitude of adjustment than the raw processing tools I typically use (Canon's DPP 4 and LR).

If I need a WB correction of more than "10" (which equates to about 50 mireds of color correction), I'm out of luck from within DPP 4 or LR. The same is true for a color temperature lower than 2000K. But if the light I am shooting under requires such extreme correction (say a night street scene illuminated by several different types of high pressure vapor lights), using the in-camera Custom WB setting at the time I take the photo allows that more extreme correction to be applied when the raw file is later opened in DPP 4.

All of the other post-processing options are still on the table as well, but I can't go back later and take my white object shot and apply that custom WB to an image unless the reference image was already loaded into the camera and Custom WB using that image was selected at the time the raw data was collected.

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