Originally Posted by HDNitehawk
Ahhh, but that comparison doesn't really address the question. As I read it, the question was 'what happens if you take the 17-55mm @ 55mm, and crop the resulting images,' i.e. by a factor of ~1.6 (1.545, actually) to an AoV of 85mm. The answer is basically the same as the APS-C vs. FF issue, cropping will increase your noise and DoF. If taking an image with a shorter focal length and the cropping it was the best answer, no one would buy a supertele lens, they'd all just use a nifty-fifty and crop the heck out of the images, right?!? [:P]