In this case, I would seriously looking at the EF-S 17-55 f/2.8 IS. This lens has everything you need-wide angle, IS, f/2.8 and"L" IQ. You can always sell it when you go full frame. IMO keeping the lens with the 50D makes a great back up for your fullframe im the future.


I'm currently using an EF24-70 f/2.8L as my general purpose lens. When I gotthe24-70the EF-S 17-55 f/2.8 IS had just come out and there weren't many reviews of this brand new lens. After knowing and hearing great reviews of the 17-55, If I could do it again I would get the EF-S in a heart beat. My 24-70 f/2.8L is a great lens, it's sharp wide open, but it's not really wide on a 40D, and Ikeep wanting more on the wide end. I just don't use my general purpose lens that much to consider selling my 24-70 and getting the 17-55. That's why I'm keeping my 24-70 f/2.8L for now.