Correct WB may not be obtained with the selected image

<p>Here's an interesting one.</p>

<p>I was using a 5D MkII the other day and using mixed lighting sources of available natural light, some tungsten and 3 speedlites fired remotely with an ST-E2. I take a shot of a large white card filling the frame. When attempting to set the white balance I get the message "Correct WB may not be obtained with the selected image"</p>

<p>Taking a shot without the speedlites was fine. White balance could be set. Also using a single speedlite on the camera allowed me to set the white balance. (If I bounced it.) Interestingly though, using one speedlite firing straight at the white card gave me the same error message.</p>

<p>Does anyone have a definitive answer as to why I cannot set the WB? I never had any problems before when using a 5D.</p>

<p>Maybe you were blowing the highlights? If everything is at full scale you can't change (or detect) the color balance.</p>

<p>I'm guessing that the image in question blew out a channel or the camera has a limit as to how much difference between the channels it will allow when doing custom WB. Remember, the WB is done by scaling the values of the 3 channels.</p>

<p>When using flash, I would use a grey card for white balance. </p>

<p>When using a modern Speedlite the AWB is recorded as a setting in the Raw file. The AWB varies depending on the Speedlite's power. Often it's an excellent or perfect starting point.</p>

<p>And yes, using a grey card starting out in the shoot is a time-honored system; however with your mix of three white sources it's technically im[possible for a "One Whtie Balance fits all" equation or solution. </p>

<p>Mixing various light sources is the kiss-of-death. It's not a camera problem. Simple Laws of Physics. Figure out something else, but make it light from one source-type.</p>

<p>OkeyDokey, Ed. I might as well just shoot it with the resulting clean pure light, too.</p>

<blockquote>

<p>Mixing various light sources is the kiss-of-death. It's not a camera problem. Simple Laws of Physics.</p>

</blockquote>

<p>On planet Earth..?<br>

You mean that using direct sunlight and reflected sunlight, esp. on a cludless day, is a kiss of death, too..? (I have just described 99% of daylight shooting conditions and these two types of light couldn't be different in terms of spectral content/temperature...)</p>

<p>And to the OP: there is absolutely nothing wrong with obtaining custom WB the way you are doing it provided that proper exposure is set first (as noted in the footnote in the manual if the exposure is way off the custom WB procedure might not work...) Also, it is better to use a gray card for this purpose (also mentioned in the manual.)</p>

<p>It appears Bob was right. Thanks for pointing me in the right direction and thanks to the others who contributed too.</p>