Canon Lens choice

I'm getting ready to purchase a lens and would appreciate some input.

The lens will be used on My 5DII
I have a 24-105.
I'm looking at either a 16-35 or 17-40
Also, if I go with the 16-35, what are the differences in the old version and the new II version?

Any and all experience and suggestions will be appreciated!

Richard, I purchased the 17-40 several years ago to replace a kit lens. I was amazed at the improvement in image quality that I got. I now also use it on my 5Dll. When reading Outdoor Photographer, I notice a lot of the folks who have their images used in the magazine note that they used the 17-40 for those shots. I figure that's a pretty good endorsement. You may get a little bit better quality from the 16-35, but I don't know if you can notice the difference for the extra $$.

If you already have any quality (i.e., expensive) filters for your 24-105, it may make more sense to go with the 17-40 because the front element is the same size as on the 24-105 and you can thus use your existing filters. Otherwise, you'll be buying new filters for the larger front element of the 16-35, entailing yet more cost and some minor hassles in the field.

I can't speak to the quality difference between the 16-35 and 17-40. I have two copies of the 17-40 (don't ask why) and they both perform almost identically: relatively sharp across the frame at f/16 but distinctly fuzzy at the corners as you open the aperture. Even at f/11, while the center is superbly sharp, the edges are not. I find this highly annoying in a $750 lens and I'm not exactly a perfectionist.

If the tree in your backyard grows hundred dollar bills just go get the 16-35 II no big deal. If it only grows ten dollar bills get the 17-40. I would lay odds that only under the most scrutinizing inspections by the pixel peepers anyone could tell a difference between the images either produce.

I got the 16-35 to go with my 5DII because the image quality was/is a bit better. I guess it depends on whether or not you are printing large prints - 16 x 24 or larger. If not, the 17-40 would be more than enough sharpness. Also, the 17-40 is quite a bit lighter if that's important in carrying your gear into remote areas.

I had the 17-40 and switched to the 16-35, if I recall correctly it is faster, less chromatic aboration in the corners, and I think it's still the same size filters as the 24-105 and my 70-200. Have to look up the filter sizes. My basic theory on equipment of all kinds is to make do with what I have for as long as I can possibly stand it, then buy the very best, and hold on to it again for as long as I can stand it.
Hence I have the 1Ds Mark II (2 bodies) for some years now though the Dx will be tempting. Or was until I saw Nikon come out with a big MP monster.

16-35 is better than the 17-40. You get slight vignetting and drop of in sharpness in the corners with the 17-40 at wide aperture. I did a direct comparison - if you are near a calumet you can rent them both and try a test. The difference was notice at F5.6 and wider/more open, so if you are shooting well lit landscapes at F8 you're fine with the 17-40.

I shoot low light and my 17-40 popped off my Tamrac belt system while shooting a tornado in 2009!! Never to be seen again...

When I bought a 5DII I also added a 17-40. Maybe I had a "bad copy", but it vignetted pretty badly at F4. and the corners were a little soft with some chromatic color. I returned it and got the 16-35 II. Much better. On the other hand I have seen some wonderful shots taken with the 17-40. Probably important to remember that CS5 has a lens correction profile for either lens in ACR that will quickly correct the faults of either lens.

Richard, It depends on what you plan to photograph. I have the 17-40 and use it for landscape photography. From what I've seen and it's true in my copy, f8-16 the 17-40 is as good or better down to the corners than the 16-35. In general lenses are designed to be at their sharpest 2-3 stops from wide open which puts the F4 series that Canon offers in the sweet spot for landscape.

There is copy variation. I refer to websites that perform lens tests to help me make a decision. It's not the only way to go about choosing but in my experience it helps my peace of mind and it gives me a base point to compare my lens. For example having purchased a Rokinon 14mm 2.8 I noticed the sample I had was softer in the corners (cursory check here) than what the review suggested I should experience. Sent it back with a note to the tech dept. They confirmed the defocusing was slightly off,made some adjustment and whatever they did improved corner performance.

17-40 vs 16-35 II This site (http://www.photozone.de/) and others like it confirms the 17-40 performs admirably in comparison to the 16-35. For me it was an easy choice once I understood the characteristics of the lenses and I thought for the price the 17-40 more than justified consideration over the 16-35.