B <snapper@st-abbs.fsnet.co.uk> wrote/replied to: >Obviously once the flash has fired there's little time to do an "auto-colour-balance" on the fly. So if it's looking at ambient lighting before the flash ... I think maybe we both missed this, but I reread this again according to your wish, and I'd like to say that AWB is something that is kind of unknown. But, we do know the 1Ds does a nice job because it has a separate special AWB sensor built in. The 10d does not and I would guess uses some kind of software sensing on the overall image. So it does do it on the fly, as well as the 1Ds, but just in a different way. I think most digital cameras likely do it on the fly too. In other words, it uses the data from the image just captured to decide how to balance it before writing it to the memory card. I could be wrong, but this is how I understand it. It's kind of like exposure metering, I'm sure it's centre weighted or programmed, so if you have a spot of colour and move it around on the background you may get wildly different AWB happening. Let's not forget that light does not come direct from our light source into our cameras, but bounces off everything in the scene before heading through the lens. How else could it determine an AWB in an almost totally black night scene using flash, but to read the image after taking it?
