Previously, I was using an SD1100 / Ixus 80 with shutter over ride script from fbonomi for aerial photography. At first, I set the script for 1/1500 shutter speed and at least half of the exposures were WAY off - either too bright or too dark. After a while, I changed the script to 1/500 and that produced around 99% good exposures.
I don't know if what I did means anything here. My conclusion was that for my settings, my camera would not shoot at 1/1500 but I easily could have been doing something wrong. Just a data point...
BTW, I subsequently judged that at 1/500, the whites were blocking up and losing detail. I changed the script to tell the exposure measurement that the speed was 1/250, got the exposure measurement numbers and then set the shutter to 1/500. The result was that the shots were slightly dark but none of them had whites with no detail. A slight contrast change in Photoshop made it all good.
