Yourlensreview - Lens - Canon EF 17-40 F/4L USM

- Contrast
- Build quality is superb, it feels indestructible
- Sharp
- Hardly any vignetting
- Very flare resistant
- Weathersealed (with a filter attached)
- Fast AF, I'm told it's one of the fastest AF-lenses ever produced.

- It isn't as sharp wide-open on 40mm as I had hoped, but it is excellent when stopped down a little.
- The hood is very wide, bulky and useless on 1.6-crop.

I bought this lens as my main walkaround lens for the 30D, and it has been everything I hoped it would be. The only disappointing thing is what I knew in advance, the sharpness wide-open near 40mm. It's still very good, but this lens has such good reviews, I was expecting even more. But from f/5.6 it is much sharper than de sensor can handle, so I wouldn't worry about it. If you need low light capability I'd recommend the 16-35, but if you don't need that (or don't want to spend the money), get this one. Also this lens is much better against flare.

My lens hasn't had much physical abuse, but I've seen one that has. And, you can't see it! The build quality is just superb, I'm not afraid of dropping it on the floor.

There is simply no other lens in it's class for this price. Therefor I highly recommend it, unless you need something faster.

Sharp
Extremely fast AF
Very good build quality
Reasonable price

Kinda soft at 24mm and 40mm

Very nice walk-around lens on 1.6x cropfactor bodies. Very well constructed,  handles flare well for a wide-angle lens.
Optically very good.

Lightweight, blazingly fast autofocus, sharp, great contrast, little flare, L-build, very wel dampened focusring, smooth zoomring

Could be a bit sharper though

Although I think it could be a bit sharper (hence the 9 at performance) it is a great lens. It's AF is just about the fastest you'll find at this moment, the range is the same as an 24-70 at fullframe which makes it a rather nice standardzoom.

I'm really happy with it, although the 40mm can be short at times, but it's on my body for about 70% of the time :)