Conclusion: The Canon EF 50mm F1.4 USM may be based upon a 37-year old optical design, but its performance in our studio tests clearly shows that it's not giving up yet. Sure the hairs are beginning to grey a little, and Sigma's new young pretender can outmuscle it comprehensively at wider apertures, but this lens really shows its quality once the aperture is closed down a couple of stops.
Pros: Excellent image quality when stopped down, Essentially no lateral chromatic aberration, Fast and accurate autofocus with full-time manual override
Cons: Distinctly soft and 'dreamy' at wider apertures (F1.4-F1.8), Bokeh chromatic aberration, most visible at wide apertures, Vignetting at wide apertures on full frame (essentially disappears by F2.8), Somwhat susceptible to flare
Canon EF 50mm f/1.4 USM - Full Format Review / Lab Test Report
19 June 2009
Conclusion: It is no surprise that the Canon EF 50mm f/1.4 USM is a very popular choice among Canon users when it comes to choosing a standard lens. It offers probably the best compromise between quality and price here. That said it's not a flawless lens when used on a full format DSLR. The contrast level is quite a bit reduced at f/1.4 and the corners are soft here. However, the results are good at f/2 and nothing short of great at medium aperture settings.
Conclusion: The Canon EF 50mm f/1.4 USM is a rather obvious choice when looking for a standard lens to be used on an Canon APS-C DSLR. That said it struggles a bit at maximum aperture - the borders are somewhat soft here, the contrast level is reduced and the amount of vignetting could be better. However, the image quality is already quite impressive at f/2 and nothing short of outstanding in the f/2.8 to f/8 range. Lateral CAs are nothing to worry about.
Conclusion: The EF 50mm f/1.4 USM showed an almost flawless performance during the lab- and field-tests both in terms of optical and mechanical quality. If I had to list a few negative points it would be vignetting and low contrast at f/1.4. So if you're looking for a lens in this class the EF 50mm f/1.4 USM is a great option.