Originally Posted by Falcon16
good point chopper duke I forgot about the fact that EF-S lenses are made for use on a APS-C body and thus produce true to focal length FOV whereas an EF lens is designed to cover a full 35mm so it gets parts of the lens that are in effect clipped by the sensor leaving the center of the lens to render the image to the sensor.
with that said Canon EF-S lens mount - Wikipedia, the free encyclopedia
if you look at that wiki article it points out that no L series lenses which I'm sure that's what Josh's 2.8 is are EF-S mount in fact the selection of true EF-S lenses appears relatively small.
It is very possible his lens is an L Series and not an EF-S. It's a canon. Ewwww.