Quote Originally Posted by mmodica
I'm gonna be getting a Canon 50mm f/1.4 USM for my next lens. First, I'll be using this lens on a 1.6x body, so I figure I can get the ET65 hood (designed for the 85mm f/1.8 USM) without getting any vignetting

Forget about step up rings - our first question should have been does the ET-65III hood for the 85mm f/1.8 lens actually fit on the 50mm f/1.4. The answer is no. The 50mm f/1.4 takes the ES-71II hood. The number in the hood designation refers to the diameter of the mount where the hood attaches to the lens. Trying to put a 65mm diameter (at the mount ring, the other end is wider) hood onto a 71mm diameter mount is proabably not quite as bad as sticking a large square peg in a small round hole, but still, it's unlikely to work very well...