I'm trying to start a timelapse at f3.5 iso1600 in aperture priority mode at night for the stars, and then have it ramp to f8 iso100 around sunrise. It is in take pics like crazy mode so there's no delay between frames. I have the settings changed just like described here but the settings don't change at the set global time. Is this because the camera has to be in M mode and not AV? This is on a 550d by the way... Thanks a lot, I'm stumped and really want to get this working ASAP!