Last night I tried to get some club shots with my 60D (with the 16-35 2.8L lens) at ISO 1600.
I had about ¹⁄₁₅ — ¹⁄₂₀ seconds at f/2.8, all in Av mode.
When I raised the pop-up flash, I hoped that the camera would decrease the time to ¹⁄₆₀ or ¹⁄₂₅₀ to freeze some of the motion, but the timing remained as it there would be no flash. I had to switch to "M" to get the desired result. I know from my 550D that on that camera there is a setting that automatically switches the timing as soon as one raises the flash. To make a long story short, is there a camera fault or did I miss a setting?