wakko wrote in post #4125059
that's cool.
Here were my pet 'dislikes'...
1. distortion at 17-24mm
2. non constant aperture (i.e. f/4-5.6)
3. IQ at 17-24 and 70-85 not fantastic wide open. Not bad stopped down.
That's about it really.
I like little to no distortion in any lens I buy (unless it's designed to have distortion). don't get me wrong... 17mm on a 5D curves a bit at the edges (by nature of a UWA).... on a 30D (what I had) it was to be equiv to 28-135. I don't reckon there should be much image distortion at the equiv of 28mm-35mm. The 17-40 on the 30D showed to have next to none.
Non constant aperture. just proved to be annoying when zooming in and out. The 17-85 has f/4 at the wide end, and 5.6 at the long end... meaning if you zoom to 85mm, it'd automatically change to f/5.6... then if you went wide again it'd stay at f/5.6 which was frustrating. constant f for me is better in that it's always f/4 from start to end... even better with the 24-70 with constant f/2.8.
IQ just seemd wayward on my copy. David (three) may tell you otherwise but after using the 24-70, I'll not look back to it again.
17-40 is a bit short for a general walk around lens on a crop... another lens to consider would be the 17-55 f/2.8 IS. I hear reports of it being L grade glass with constant f/2.8 and IS!

.. if you look after your gear, it'll serve you well (some copies have dust issues).
hope that helps.
edit: I found that cos most of my shots were at 24-70 anyway, that this lens suited me more. Some find it a bit long at the wide end on a crop body... now I have a 5D, it's even better for me... I don't miss the length one bit

Thanks (again
) for the info - as before, lots for me to learn. I have found that I'm using 18-55 mostly, and not often at the 18 end. I'm trying to be practical and get me something that'll cover a range of uses too.
I get it now re the fixed vs variable f-stop, shouldn't pose too much of a problem as I tend to check each time anyway.
Whilst I might lose a bit in the lack of L lens in 17-85, the IS is an attraction for me. This means it could be used indoors without too much hassle, (without flash), or lowlight outside. I'll have a look at the 2.8 IS you mentioned.
As you've said before, it's a bit of trial and error to see what suits and what I'm photgraphing mainly. I just don't want to end up with a lot of unused glass in the bag.
Cheers for the heads up, Feng 