Gosh. Am I the only champion for this "underwhelming" lens? Where I am it's an $800 L lens. It's not the sexiest beast by any stretch but as I said I have found it slightly better than the 10-22. I agree it has more distortion than the former- marginally - but anyone who is concerned about correction of this affecting corner performance should take a reality check. I'm all for pixel peeping - believe me I'm obsessed - but I know enough to know that correcting in LR makes no discernable difference at all in reality. We can choose to ignore that fact for the same of spending $$$$ more for no 'real' difference or we can just roll with it. I spend a lot of time mulling over the former but generally settle on the latter: reality.
I too will be keen to look at the new alleged UWA zoom in the pipeline but for now the 17-40 is doing a perfectly good job for me. I also appreciate the extra length relative to the 10-22 (or by comparison the 16-35).
Interestingly I used my 24-70l quite a bit on a recent trip and I found I was getting just as much distortion and in some instances more out of it than my 17-40 for certain shots. Which surprised me.
When I say underwhelming I compare it to the EF-S 17-85mm (yes, the $ 350 lens) and 10-22 I had at the time on 7D as well as the 24-105mm on the 5DII.
I am not talking about pixel peeping- but the colors and the sharpness were just not great. This is, of course, subjective. YMMV, so I am sure there are hundreds of people who are perfectly happy with their 17-40.
Additionally, on a crop sensor Rebel with limited ISO capabilities, IS is often necessary for the 17-40mm focal length with f/4 or smaller.
Yeah, fair enough, it's a personal view and there's no way I can argue with that.
My experience is certainly quite different. I must have a good copy because I can't be more impressed with mine to be honest. It was probably the most unexcited I've been in buying a lens (at the time) as I was effectively replacing my old 10-22 but I was quite surprised at a number of things with regards to how it improved the IQ of my night photography: much cleaner and punchier starbursts, better and less lens flare (but slightly odd flare from time to time), and stronger and more impressive colours. I do believe the 5D2 sensor has a bit to play with the difference but it cuts to the nub of the original poster's comparison query.
I agree the 17-40L has a fair whack of distortion but I don't see it as anything terribly unusual.
For me (personally), I enjoy the zoom aspect at night as it means I can get a shot quickly without pacing around. I did consider using the Zeiss 21 for awhile but decided that the 17-40 was better suited to the more quickfire guerilla style photography of night stuff. So it really suits me.
As for comparisons with the 16-35L, several other posters have nailed it appropriately. As I understand it (and I cannot speak from personal experience, granted), the IQ comparison between both is not significant and most crucially, the 16-35 is advantageous in a more photo-journalistic sense as opposed to the more traditional tripod landscape usage given the 1 stop faster aperture. I have READ that the 16-35 exhibits equivalent (if not worse) corner sharpness. Again, I stress I haven't tested it for myself. I think both would fit well into a cash-flushed (or pro) camera bag. The 17-40 is also far handier to lug around at night (or up hills) than the 16-35 on account of it's comparative weight. But it would be a dog in a late afternoon or evening.
The final advantage of the 17-40 is the slightly improved reach. Might not seem like much but I'm happy to have that extra zoom when compared to the 16-35ish equivalent focal length of the 10-22.
There's no doubt to me that at a pixel level, both lenses are not stellar. The alleged new Canon UWA zoom, the Nikon equivalent and the Zeiss ZE 21 have the advantage but for the relative cost of the 17-40 I reckon it's a good alrounder that I'm happy to settle on for the moment and it hasn't harmed my IQ/photography in the slightest (and for whatever it's worth, I pack a bit of L glass so I know what good glass is).
For reference, mostly everything on the page below has been taken using the 5D2 and the 17-40L. Processing has just been colours/contrast etc and the usual RAW fix-ups. No HDR silliness. The lens is a little champion, in my opinion.www.facebook.com/waynegrivellartandphotography