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
Summary: Although not pin-sharp at its widest apertures, Canon’s EF 50mm f/1.4 USM remains a competent performer and its image quality between f/4 and f/8is excellent. Two issues should be considered when assessing this lens: the size of the sensor on that camera with which it will be mainly used and whether the types of images you take will be affected by the inherent imperfections in reproduction.
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.