Let me start out by saying I'm a hobbyist and photography is not how I make my living...

I work for a company that supplies structural steel to the commercial GC's all over Texas. I use this lens to take great pictures of buildings! I can get up close to the building and take a great picture with a lot of crisp detail in the foreground and bokeh in the background. Without it, I was using a 50 or 85mm and I would have to stand too far away and would loose the detail up close.

Limitation: One thing to note is that on a 10D, the lens is so big that the integrated camera flash will cast a shadow in your pictures. This is not a problem with my 30D (or with a speedlite), but it is a problem when my father uses it on his 10D and didn't want to take a speedlite.

Overall, I really like using this lens and use it a lot... in fact, it stays on my camera 85% of the time.

Although I am very new to the SLR world I made the jump right to this L series lens and I love it. Super sharp images, great color, very fast focus, and having 16mm to play with at the wide end is a lot of fun. There is definitely some light fall off at the corners with the aperture wide open, but stopped down it isn't really an issue. There is slight distortion at the widest angles but I kind of like that effect to I'm not bothered by it. I shoot a lot in overcast and dark conditions so the f/2.8 is great. The only thing I have been struggling with is flare in bright conditions. Pointed near the sun at 16mm even with the hood on you still have to be careful. Like I said, I don't have a lot of experience yet so I can't say if this is normal or not. The flaring isn't anything so damaging that it cannot be corrected in Photoshop. I'm extremely pleased with this lens!

On Feb 22, 2007, Canon announced a "II" version of this lens that will correct the optical performance problems this lens has. The new lens has been completely redesigned, and will require MASSIVE 82mm filters. Yikes! I do not own this lens, as I am now waiting to see if the II version will be more expensive, or if this version will drop below $1000. As mentioned, the new version will require 82mm filters, which will be even more expensive than the filters the I version uses.

The II version has now been listed on Amazon. It looks like the II will be about $300 more, rather than this version dropping in price (so far).

buy it, if you have the cash.

- its canon 'L' series lens, best glass money can buy

- lovely colours

- fast focusing

- super wide zoom

- and not that heavy or bulky (as other would say)

I do fine art photography and mainly use L primes but have kept and use only three of Canon's zooms. This is one of those three. Lovely color, fast to focus and uses all the 5D's full frame and DR. If you are going to have a Canon wide zoom for 35mm and under this is it.