So I was wondering if anyone can explain the basics of HDR photography using a canon t2i. Is there a way to set the camera to automatically change the exposure level, or do I have to manually adjust after each shot? Also could you recommend what to set the exposure at if manual is my only option? Or is it more of a trial and error experiment type of thing. Once I have the images how do I combine them in aperture? I've seen hydra on the apple.com/downloads section. Is this my only option?