I have recently used this lens for landscape and seascape images in mostly good outdoor light on two full-frame cameras, namely the EOS 5D and EOS 5D Mark III respectively. Although it covers a range of focal lengths I already had mostly covered by three prime lenses, I did not previously possess...

Robust and impressive build quality with smooth handling; relatively lightweight; reliable autofocus; familiar vibrant Canon colours; Well priced (at least by 'L' standards)

Very weak corner resolution at 17mm below f/11 on full-frame; The bulbous and ugly lens hood is large, obtrusive and awkward to pack unattached

A lovely lens for the price, very fast to focus and very quiet. I use it on a 600D body so only use the centre area of the lens. I suffer no curving on the edges as full frame sensors are reputed to suffer. As you would expect for a "L" series lens, it's built like a tank with weather sealing.

Consistent Output; Easily Interchangeable; Quick Focus; Rugged; Sharp Focus; Strong Construction

The Canon EF 17-40mm f/4L USM ($839.99 direct) is an ultra-wide to normal zoom lens that is compatible with Canon EOS SLR cameras. When used on a full-frame body, the lens provides an extremely wide 17mm field of view on the wide end with a 2.4x zoom factor that takes it to a normal 40mm field of...

The Canon EF 17-40mm f/4L USM lens is an inexpensive alternative to the 16-35mm f/2.8, but its edges are muddy at its widest angle. (3 out of 5) Pros Ultra-wide field of view Reasonable price tag Good center sharpness Cons Muddy edges and corners at 17mm Some distortion Noticeable color fringing The...

Ultra-wide field of view; Reasonable price tag; Good center sharpness

Muddy edges and corners at 17mm; Some distortion; Noticeable color fringing

It's not exactly easy to design a flawless full format lens and the Canon EF 17-40mm f/4 USM L shows its part of the struggles here. The lens is not overly fast but it has a comparatively broad range for a lens in this class and it seems as if Canon has overstretched things a little with respect to...

Gary Wolstenholme takes a look at this popular lightweight ultra-wide angle zoom lens.

Superb performance in the centre throughout the range; Well built; Lightweight

Sudden softness in the corners may disturb full-frame SLR users; Distortion difficult to correct entirely at 17mm; Falloff at 17mm

The Canon EF 17-40mm may deliver spectacular ultra-wide angle coverage when fitted to a full-frame body like the EOS 5D, but offers a more normal, general-purpose range when mounted on cropped bodies like the EOS 30D or 400D / XTi.

Canon 'L' build and optical quality; Fast and quiet USM focusing motor; Constant f4 aperture throughout range; Will also work on full-frame body

Shorter zoom range than kit lens; No IS (although not particularly necessary; Overkill if not considering full-frame in future; Canon EF-S 17-85mm more flexible for most

I bought this lens while I was away in my Military training, and coming back home to find me a nice looking lens. The condition was mint, although with some scratches as mentioned. I kept it safe and sound in my bag and used it 2 times without any problem. On the 3rd usage, the zoom did not work.

I own this lens for 3 years. It is simply great on crop. Dust and Rain is not a problem. Light weight make it possible for camera to be on your shoulders all the time in bike tours!

Build like a tank; Great lens for travel; You should try hard to broke it! Lowest weight for L lenses; Cool for APS-C

Distortion on full frame; My copy isn't sharp at corners (not a problem on crop

a good lens at a bargain price, but if you want the best IQ you need zeiss prime lenses

cheap; light and good image quality

corners can be really bad at f4