Thanks for the info Blazer!!!
Ok, I was pointed toward this link on fredmiranda to help explain the 1.6 form factor...
http://www.the-digital-picture.com/C...op-Factor.aspx
So if I read this correctly, EF-S lenses are specifically made for 1.6 form factor bodies... What would happen if you used an EF-S lens on a 5d or other FF body??? Just wondering...
Also what do you all think of the Tamron 17-50... That was another lens suggested to me... As well as the Canon 50mm f/1.8 as a good cheap lens to pick up for taking pics of the tank...