17-85mm f4-5.6 IS VS 24-70mm f2.8 L QUESTION

I just bought my first L series lens (24-70mm f2.8L) and taking a few shots, I've noticed that it's not too different from the 17-85mm I have.

Both are sharp and take good photos. Maybe my expectations were too high with an L series lens, but am I missing something? At the same exact settings (aperture, shutterspeed, lighting) the 17-85 actually looks a bit sharper.

Or is it that the 17-85mm is a GREAT lens? I don't know. Any Canon owners who have any experience with these lenses care to shed some light?

Put the 17-85 to the camera and set to the AV mode. Zoom it to 75mm, dail it to f2.8 or 3.2 or 3.5 or 4.0 or 4.5. Oops, cannot be done. The 24-70 is 2 stops faster in the long end compared to 17-85 (2.8 vs. 5.6), that makes a hugh difference in low light situation and to create a shadow DOF. I am sure that 24-70 at 5.6 (2 stops down) will be much sharper than 17-85 at 5.6 (wide open). Your statment of both lenses are equally sharp is probably true for f8 or above.

Put in the 24-70 to the camera and set to AV mode. Zoom it to 17mm. Oops, cannot be done!

They are lenses for different purpose.

yes, you have a very good copy of the 17-85..........i find the same to be true with my 16-35 and 24-70 vs my 17-85. you won't get the edge to edge sharpness of either L's that cover this focal length with the 17-85, and your 17-85 will definately let you down when using AF indoors not to mention that you will never reach the shutter speeds of the L's...........but for the most part, the 17-85 is a great lens...............now the problem you will have (and it's why i'm adding the 24-105L) is being satisfied with any of the images from the 17-85 once you really start using the 24-70 more and more. you have most likely also noticed that the speckly viewfinder screen you see with the 17-85 is not as pronounced when using the 24-70.
my suggestion, forget about using the 17-85 for a good while.

>>Or is it that the 17-85mm is a GREAT lens? I don't know.<<

Past reviews of the 17-85 have criticized it for not being sharp...an improvement over 18-55 kit lens, but not a standout. Strange test results, in my opinion, since I tested my Tamron 28-85 f/2.8 which has been rated as very sharp, and compared it to my 17-85 and 70-200 f/4L and the 17-85 was no slouch even shooting test patterns and pixel peepeing! And now you come along a find similar results vs. the Canon 24-70 L, too!

I got the same results comparing my 17-85 with a 17-40. I could find no difference in sharpness, only higher distortion at 17mm. The extra range of the 17-85 made it the keeper.