I am going overseas this summer and wanted a general purpose prime lens in order to travel light. I wanted a lens that would give me a 45mm "standard" perspective from a 20D, however, having read the abysmal Canon 28mm reviews, and owning the 35mm f2.0, but deeming it too long for my intended purposes, reluctantly purchased this lens hoping that it would be a fair compromise. Unfortunately my fears were realized: Not only is the 24mm focal length not sufficient for the types of shots that I want to take, but overall I was not impressed with the lens itself.
As a happy owner of the 35mm f2.0, I was expecting a similar size, feel, and quality to the 24mm. As reference, I would like to address differences between the 24mm and 35mm that I did not read about when reviewing this lens:
-The 24mm is about 1/4" longer than the 35mm, however, it fit very snugly onto my 20D and felt more robust than my 35mm.
-The 24mm has a much larger front element than the 35mm which may warrant a filter if you feel skittish about exposed glass.
-The 24mm internally focuses, as opposed to the 35mm which has a rotating head.
I found the 24mm AF to be just as responsive than the 35mm, if not slightly more so and aesthetically it looks and feels great.
The downside to this lens, which surprised me given its rave reviews, is the image quality. The corners on my copy, even stopped down to f4 and beyond exhibited slight vignetting, corner softness, and unacceptable amounts of chromatic aberration--I felt like I was using a Sigma.
This lens is being promptly returned and I certainly hope the 28mm f1.8 that I'm purchasing in its stead will defy its reviews and serve my purposes better.