24-105 vs 15-85 on 7D: Help me choose

I would normally recomend the 15-85 in this instance but as you already have a 10-20 you don't need that extra width.
I personaly think 24mm is too wide for a crop sensor walk around lens so if you want to be changing lenses all the time get the 24-105 to go with your 10-20. If you want a single lens you can take out and not have to cary any extra gear, get the 15-85

Some people need lenses with red rings on them to help with photographic confidence

Mornnb wrote in post #14835277
How does the 24-105mm compare to the 15-85mm in sharpness, and colour/contrast quality?

I would say there is not enough of a difference there to justify changing from one lens to another if you already have one. Switch for focal length difference; switch for aperture difference; switch for build quality difference, but not for IQ.

Milutiche wrote in post #14836450
...
I personaly think 24mm is too wide for a crop sensor walk around lens ...

I have often heard the opposite, 24 being not wide enough on crop.
I have got the 10-20 and 24-105 combination for that reason and enjoy it.

Milutiche wrote in post #14836450
I would normally recomend the 15-85 in this instance but as you already have a 10-20 you don't need that extra width.
I personaly think 24mm is too wide for a crop sensor walk around lens so if you want to be changing lenses all the time get the 24-105 to go with your 10-20. If you want a single lens you can take out and not have to cary any extra gear, get the 15-85

Some people need lenses with red rings on them to help with photographic confidence

I assume you mean 24mm is not wide enough rather than too wide.

(a) Rent one or buy one.. try it and then decide whether 24mm is good enough for your kind of needs.. or (b) Analyze your photographs and see if most are taken on 20+ mm or most are on widest range you have now..

Whenever you see lens choice thread reaching to multiple pages,it ends up in confusing state.. finally you end up introspecting, listing down needs, putting "must have" vs "nice to have" and then go for it.

I have been using 24-105 on my T2i since more than a year now. I used 15-85 and did not like it for (a) distortion (b) inconsistency... then I got 17-55 and was amazed for its consistency, but it was too short on long end for me.. so 24-105 was the only answer!

mwsilver wrote in post #14837459
I assume you mean 24mm is not wide enough rather than too wide.

hennie wrote in post #14837318
I have often heard the opposite, 24 being not wide enough on crop.
I have got the 10-20 and 24-105 combination for that reason and enjoy it.

yeah I got that wrong, Not wide enough

if you plan to stay with the crop body I would go for 15-85 it looks pretty much alike to 24-105.