Quote Originally Posted by Sheiky
I liked the imagequality but the longer I used it the more I hated the af performance, speed and accuracy, especially in low-light and or party-environment.

My experience is that the 17-55 is not going to do any better with autofocus. It will be quieter is all. I think upgrading from your 50D to the 7D would make more difference to autofocus.


Quote Originally Posted by Sheiky
I can't decide between the canon 17-40L and the 17-55 is usm

There's no contest. The 17-55 destroys the 17-40 in almost every category. The only superiority of the 17-40 is in the weather sealing, build quality, and full-frame compatibility.


If your whole reason for upgrading is autofocus, then the 17-40 would be a huge step backwards. It does not even activate the f/2.8 autofocus sensor in your camera, which is far more accurate than the f/5.6 sensors that the 17-40 uses.


Quote Originally Posted by Sheiky
-sharpness: I hear a lot of different opinions about this matter. Some say the 18-55 kitlens even outperforms the 17-40. That's hard to believe for an L lens. So I hope you can clear this for me. I really like detail and sharpness. I'm used to watching my photo's at 100%

It's true. The cheap, lowly 18-55 kit lens blows the 17-40 out of the water:


18mm at f/4.0


24mm at f/4.0


28mm at f/4.5


35mm at f/5.6


The other cheap lenses are even better. Your previous Tamron 17-50, or the Sigma 18-50, and of course the Canon 17-55 all do better than the kit lens, so they are in a different league than the 17-40.


It should not be surprising or hard to believe. The 17-40 is like a big commercial truck that can carry 30,000 pounds at 60 MPH. The 18-55 IS kit lens is like a small sedan. It can drive twice as fast as the truck (60 MPH), but it can't tow 30,000 pounds. It is much sharper than the 17-40, but it can't be used on full frame. The 17-55 f/2.8 USM and Tamron 17-50 are like sports cars. They drive even faster than the 18-55 kit lens, but they still can't be used on full frame.


If you want to see the 17-40 shine, you *have* to put it on full frame. Compare the 17-40 on full frame vs. the 10-22 on APS-C and you'll see what the 17-40 was designed to do.