OH! Is what you're trying to do is have the shot snap from one "focal length" of the lens to the next focal length immediately? The default tweener on Carrara is a bezier curve, which would make the camera zoom from 100mm to 28mm over the time between key frames. If you want the render to snap from 100mm to 28mm, you'll need to change the tweener to discreet (I think that's the term; I don't have Carrara open in front of me now.) Just double click on the timeline between the keyframes and select the different tweener mode. (There are several -- bezier, linear, oscillate, discreet, maybe another one or two I'm not remembering.) Hope that's helpful! - Dex