Summary: I was really excited for this lens and I couldn't wait to use it for a family function. I don't consider myself a professional photographer but i am constantly using my DSLR and taking pictures but I was very disappointed with this lens, I am sending it back immediately. The pictures were to soft at f/2.8, they started getting sharper at f/4.0. I'm using the money I get back to buy the Tokina 11-16mm f/2.8. But overall, i recommend you don't get this lens.
Conclusion: I've had this lens for several years. The images are soft at all apertures. There's a color cast. There's massive vignetting, though PIC removes it pretty well. You'd be better served to save your money for the 17-40 zoom.
Cons: Semi-sharp images, color cast, intense vignetting
Excerpt: This lens has significant vignetting issues. The color output is also questionable. Some of these things can be corrected in PS, but if you're serious save and get better glass. The lens felt solid and the build quality was good, but it just does not deliver the image quality you'd expect from Canon.
Summary: I used it to shoot from an elevated angle. The result were disappointing.....I paid $[...] but I don't think it is even worth more than $[...] to tell you the truth. The colors are lifeless, "burnt-out". There are no details on the images. You can see the samples on my site: [...] Look for the huge house with the red roof. You will see what I am talking about. Normally, I use the 17-40 L on my elevated system.
Summary: I wanted a 20mm prime to use for night shooting, so I thought I'd give this one a try. I chose poorly. Returned it the same day. Still on the hunt for a good prime night long exposure performer. This lens was really soft around the edges (even on my 40D with a 1.6x FOVCF). Although I don't need a fast focusing lens for night use, this lens still focused slowly during its day use. It's grossly overpriced. Should be only $299 at most.
Summary: The lens is okay on a 1.6 crop factor digital camera, but it isn't particularly wide-angle then (32mm field of view). I hear that it is okay on a film camera, but I have no experience. On a full-frame digital camera, it stinks....Digital cameras can be affected by the angle a lens causes light to hit the sensor, and it seems to make a difference here. The lens produces smudged, blurry images on my full-frame camera.
Summary: I bought this lens to get a bit wider than The 28-135mm IS which was my first lens for the new 10D. I liked the reasonable size and that I could share the 72mm filters with the 28-135IS. I am not happy with the sharpness of this lens at any f/stop and will not use it at all wide open. I don't know if this is a bad copy or not but since I don't have a warranty to return it to Canon; I will soon E-bay it off.
Pros: Low used price. I like the size and weight. I can share filters with my 28-135mm IS. I like the focal length.
Cons: This lens is not as sharp as I expect from a prime and is not as sharp as the 17-40L that I replaced it with.
Summary: Kurzfassung: Plus: - Gute Verarbeitung - Großer Weitwinkelbereich Minus: - Leichte Verzerrungen der Bildränder - Sehr starke Chromatische Aberrationen - Bildschärfe erst ab Blende 5,6 akzeptabel Ausführlich: Die Verarbeitung des Objektivs ist sehr gut. Und ich war sehr positiv von dem Weitweinkelbereich überrascht. Genau sowas hatte ich gesucht. Schon beim Fokussieren sieht man Verzerrungen der Bildränder. Was bei so einem Weitwinkelbreich aber durchaus akzeptabel ist.
Summary: Es war vor 20 Jahren ein spannendes Objektiv, mit den heutigen Anforderungen moderner Sensoren kann es allenfalls an einer Halbformatkamera noch befriedigen. Warum Canon so alte, untaugliche Objektivrechnungen weiterhin anbietet, ist mir ein Rätsel. Heute ist praktisch jedes Zoom schärfer und hat weniger Abbildungsfehler. Besser das richtig gute Zeiss 3,5/18 mm kaufen und auch das Canon 4,0/17-40 mm zeichnet besser, wenn auch beide weniger Lichtstark.