I have owned the Canon 17-40mm f/4.0 L for a couple months now and I remain highly impressed with it. Yes, admittedly I really wanted the Canon 16-35mm f/2.8 L but at twice the price – around $1,460, that was just more than I could afford.
My 17-40mm is my first L lens so I was very excited to own it. And the price is pretty reasonable for L glass. $700 new and $550ish used gets you an ultra-wide that goes great with a cropped or full sensor Canon.
My 5Dmk3 is full frame, and there are really very few ultra-wides to choose from. All the non-Canon lenses seem to fit crop bodies only.
So why did I buy it? I wanted a lens that was A. Good for video. B. Great for landscape. C. Great for Architecture. And D. A good walk-around lens, and it is all of those. It’s just got great range. 17mm is just stupid wide. It’s quite easy to get your feet in the shot if your aiming down a little. 40mm is a wonderful length for near eyesight framing. (It would be 55mm on a crop body.)
I say “Good for video” not great because the better and lower the f-stop the less grain you will get in video. f/2.8 and lower is ideal. Shoot in a dark church and you will see what I mean. At f/4 and shutter speed 1/50th, you will have to pump your ISO up to get a good exposure in a low light situation. On the full frame Canon 5Dmk3 and 6D they are such good ISO performers you can shoot at higher ISOs, where as the same high ISO may produce noticeable grain on a crop sensor 60D or 7D. So it’s for this reason full frame is ideal, though it helps… It doesn’t solve all low light issues.
Don’t forget there are grain-removing plugins for your editing software.
So I highly recommend this lens for full frame Canons. It’s also great for a crop sensor but if you’re doing a lot of low-light video or still shooting you might instead consider non-canon ultra-wides made for crop sensors, like the Tokina 11-16mm f/2.8.
I’ll add some sample pics and do a video review soon. Please comment with questions.