I'm sure I'm right in thinking that the new EF-S lenses are built so that the whole of the lens is used and not just the centre 2/3rds. Images from the lens I have mentioned above are as stunning as anything I have seen from my 24-105, which whilst an L series lens and very good, is still not the best of the L series bunch. I'm sure L series lenses on a crop camera are great, but so are the more costly EF-S lenses. Their only let down is build and lack of weather sealing, so if that is worth a few hundred £s extra to have that's fine. If I was to pay double the money for a lens to fit on the 7d than was necessary, I would want a pretty good reason to fork it out. It surprises me how many people do though.
