Okay, not the worst, that dubious distinction goes to the flakey old Stigma 17-35 POS.

But I've been playing with this highly-touted lens for the past week and I find it very disappointing. Autofocus in moderate light is horrible. It does not seem any sharper at f/8 than wide open at f/4 - and that's not especially sharp. And I see purple fringing in high-contrast areas, though this lens was known for NOT doing that.

This must be the most overhyped lens ever. Both my old Canon 28-135 IS and Tamron 28-75 XR Di lenses were sharper at comparable focal lengths.

Sure, I may have a bum copy. But from what I've read on various review boards, there seem to be quite a few bum copies floating around.

This one's going back to the shop, in exchange for the new Tamron 17-35mm.

:x

Noted. I'll be staying away.

Sounds like a neat lens--too bad it doesn't work.

A crappy "L" lens? What's the world coming to?

wow .. thats gotta suck .. mann theres alot of fanatics around these days
...

As you may know, I didn't trade it for the Tamron as expected.

Instead I got the new Sigma 18-50mm f/2.8 DC lens, which I'd say optically is at least as good as what I've seen from "good copies" of the 17-40L. The added focal range makes the Sigma a better walk-around lens on an APS-C size sensor, and at f/4 it's really sharp.

People rave about that particular Canon lens, but maybe that's because Canon's wide lenses just aren't that great! Honestly I've seen some great pics from it, but I've heard quite a large number of problem stories too.

Interesting interesting....

No doubt the designers of the Sigma would be at an advantage, as the lens is designed for a digital image sensor, whereas the Canon is designed for real () cameras.

Perhaps it's not a true apples to apples comparison? But I guess at the end of the day, we're talking digital and you use whatever suits your needs best!