Used to L lenses and this lense certainly doesn't focus quickly when compared to them....not nearly as expensive though.
Ok, I've had a lot of time to play with the lens now and it works very well for the money. I found my copy on craigs list and focus was right on, though slow when compared to my L glass, but it was significantly less money.
For the money, this is a great lens and I've been able to get some really fantastic shots out of it.
Well built, seems image quality good wide open on full frame, price is RIGHT.
Does flare easily
Took some time to find a good used copy off of the net for a reasonable price and so far I'm very satisfied. I've only had an opportunity to play with it for a few moments, but so far I really love the thing. I have a 17-40L among other L lenses and while I wouldn't compare the sharpness to my 135 2.0, it is quite impressive for the price to be sure. Seems good even wide open. I really like the super close focusing ability as you can get some interesting perspectives.
Here are just a few samples - If after extensive testing I find that my opinions change, I'll update the review.
I've only had the lens for a day and using with a 5D MKII, but I like it so far. I have a 17-40L, but I wanted something wider for a different perspective....I don't plan to use the lens except for at 12mm and it seems like a quality alternative to a 14mmL considering the price difference!
Here's a couple samples just for fun (first one cropped):
I was missing a 50mm prime in my bag and for once, I decided not to get L glass as I've lived without a 50mm for quite some time and wasn't sure how much I'd use it. Well, I picked one up off of craigslist after reading the reviews here and was worried about focusing problems, but so for mine is great on a 5D MKII. I've never had as good a lens for under $500, so I'm impressed. Maybe the 50mm 1.2L would be better, but I'll bet I wouldn't get ~$1000 more value out of it. I feel like I got a bargain....
Ok, so it's not perfect. It's not Canon quiet or canon quick while focusing, but I have those lenses in the bag.