I don't know about the EF-S 15-85 f/3.5-5.6, but I use a 24-105 f/4 L on my 7D for mid-range shooting biased to the long side. The image quality is excellent.


That said, as Sheiky points out, you should consider the 17-55mm EF-S f/2.8. I use this more than the 24-105mm on my 7D as the range stretches nicely from quite wide to mid, and I find this to be my most useful general purpose zoom range. There is no significant difference in image quality between these lenses, if anything the 17-55mm is a little sharper towards the edges. Also, the wide f/2.8 aperture is always good to have.


Richard