I'm renting a Canon 5D for a wedding (it was either that or a Rebel XSi for ~10% less). I'm picking it up on Wednesday and the wedding's on Saturday, so I'll only have 2 days, really (Thursday's travel) with the camera before I need to use it for "real" shots. It will be my first time with a full-frame digital, but I used to use an old film Nikon so I know what to expect there (the lenses will seem to have less reach, I'll be able to get shallower dof with the same field of view, and even my L glass will have some sharpness and vignette issues at the edges). But, I was wondering if there are actual quirks of the camera, like, don't go above ISO 800, or, the EV compensation is generally off by +1/3. Anything from previous or current owners?