A great general purpose Wide angle zoom lens.

Canon's EF 17-40 4L USM brings together precision optical design, blazing AF, durable construction and silky smooth zooming

Very sharp, light, fairly compact with versatile wide angle zoom

the internal zoom is nice though and the action is as smooth as silk.

This lens has Auto Lens Vignetting correction using peripheral Illumination control see Auto Vignetting comments belowButtery smooth zoom and manual focus ringsFits all Canon EOS cameras including full frame film and 5DFirst copy I got was good to go with no quality control issuesSharper on the wide end 17 to 24mm then Canon EF-S 17-55 F/2.8 IS and Canon 24-

The "L" zooms are a little bulkier, but very managable.

A really superb wide angle zoom, that "feels right" in your hand, at a reasonable price.

The build and operation though are first class silky smooth zooming and focus rings

It's dual purpose capabilities both as a normal walk around zoom (27mm to 64mm) on cropped sensor cameras and ultra wide zoom (17mm to 40mm) on full sized sensors make it a very versatile lens you won't out grow

Since most of my work is with long-lens and fast (and expensive) zooms, I couldn't pony up the bucks for Canon's superwide f2.8 zoom

Got this to have a nice wide zoom for my 5D mkII, and I love the lens.

The zoom is so fast and

Built to last forever with smooth zoom and focusing and they came with a lens hood and carrying bag.

Some of the main competitions (sorted by price):- Sigma AF 17-70mm f/2.8-4.5 DC macro: Good zoom range with macro, and generally solid performance if you can get a good sample

But sharpens up a lot in the corners by going to F/4.5 and is as sharp as it's going to get by around F/8 where it seems about as sharp as any zoom I have and is approaching the sharpness of a prime lens at 17mm

(especially between f/5.6 and f/11 at night!)- lightweight for L glass- non-extended zoom- good zoom range...makes it a versatile walk-around lens during the day- excellent performer on a 1.6x FOVCF body (I used it on the XTi, 10D, 30D, and 40D).

If you feel the need for a perfectly satisfactory wide-angle zoom or primary lens, but don't want to break the bank to get the best one, this is a good lens to consider

If you're looking for a wide angle that offers enough zoom with the clarity and quality that these series of lenses offer, I highly recommend it.

Very sharp, light, fairly compact with versatile wide angle zoom

The Canon EF 17-40mm f/4L USM Ultra Wide Angle Zoom Lens fantastic for wide shots and landscapes!

Unlike EF-S 17-85 F4-5.6, which is a feels like a decent consumer zoom, EF 17-40 F4L is built like a tank and has weather sealing