In the manufacture description they say that the WhiBal is a gray card. But then in one of the first tutorial videos they say the WhiBal cannot be used to set exposure/metering the scene, only white balance.
On other "Gray Card"products (say at B&H on-line) they describe their targets for both setting White Balance and Exposure. I'm guessing they are referring to using the white side for white balance and the gray side for exposure?
So, can I use the WhiBal for exposure or is it not a true 18% gray card?
As a secondary question, I'm using a Canon 5D MK III. Can I do an in camera custom White Balance using the small pocket size WhiBal, even though it's not filling the viewfinder if I use the center AF point and Spot Metering? I guess the same question applies to the larger target like the Lastolite white/gray target.