p.1 #1 · EF-S: Canon's first short back focus lens
Together with its new EOS300D digital SLR, Canon introduced the EF-S18-55mm/3.5-5.6 lens. This S indicates short back focus, which means this lens uses the extra room the back swing of the mirror in the 300D makes. By doing so this lens has a good wide-angle performance in a very light and compact barrel. The lens doesn't cover full frame though and is meant to be used on a 1.6 cropped sensor like in the 300D body. A rubber ring prevents the lens to be mounted on any other EF mount camera that doesn't have the back swing mirror.
The question now is, is this lens the first of a Canon EF-S series or just a single kit lens? My bet is that more S lenses will follow. A strong indication is the release today of Canon's MkII of the extension tube EF12 and EF25. These extension tubes have specifically been developed for the EF-S mount and work together with the EF-S 18-55mm zoom.
Together with its new EOS300D digital SLR, Canon introduced the