harrydog wrote in post #4488768
Not me. I have both lenses and my 24-105 is clearly the better of the two.
Heh! I think this discussion is a good illustration of why it's good to "look before you leap!"
The 17-85 was an upgrade to the original kit lens for the APS-C cameras, and a very nice upgrade. For a long time it was the best "walk-around" lens for those cameras. The newer 17-55 2.8 IS is now "the best", and for those looking for something better than the 17-85, that's the lens to get. But still, there's nothing shabby about the 17-85 -- I wouldn't hesitate to pop it onto my 30D for all-around usefulness.
I'm not sure why so many APS-C owners seemed to have jumped on the 24-105. This lens was made to be the kit lens, the "walk-around" lens for the full-frame 5D, and for full-frame cameras it gives a range of focal lengths that is similar to the EF-S 17-xx lenses give for the APS-C cameras. But I'm not sure what the 24-105 adds for the APS-C owners -- a lot of overlap with a bit more reach, but there are other choices that might serve you better.
As far as the "L" factor, yes, the 24-105 is the "kit lens" version of an L lens. As such it has higher specs for both build and optical qualities, but that doesn't mean that you can't get great pics from your 17-85 that rival pics from the L lens. It just means that the L optics are designed to be more consistent across the range of f-stops, focal lengths and edge-to-edge. The latter quality, though, will only benefit full-frame cameras.
If you have an APS-C camera, I'd suggest not leaping to the 24-105 just to have an L lens. As I said above, if you want an upgrade from the older 17-85, get the fantastic 17-55, and then I'd suggest taking the time to make wise choices -- some good primes (including the great 85mm lenses), the EF-S 10-22 UWA, and one of the 70-200 lenses would boost your shooting abilities more than the 24-105. At least, that's my opinion.
By the way, I got the 24-105 as a kit lens with my 5D, and do use it when it fits the bill, and I'm happy with it in that way. I'm not putting this lens down, just suggesting that it was designed to fill a particular role -- with the full frame cameras.