Canon's mid-range 50mm prime with USM, a step up from the nifty fifty for over 30 years.
The Canon EF 50mm f/1.4 USM launched in 1993 and has remained in Canon's lineup for over 30 years. Positioned between the budget f/1.8 and the premium f/1.2L, it offers a faster aperture than the nifty fifty with ring USM autofocus and better build quality.
Optical quality is good with sharp results from f/2 onwards. Wide open at f/1.4 there is visible softness and chromatic aberration but the rendering is pleasing for portraits. Ring USM is fast and silent with full-time manual override. Build is substantially better than the f/1.8 with a larger body and 58mm filter thread.
Canon EF mount only, 58mm filter thread. The main concern is the AF motor which is a known weak point. The motor can fail with a characteristic grinding noise. Repair is possible but expensive relative to the lens value. The Sigma 50mm f/1.4 DG HSM Art is the obvious alternative.
Moderate value used but the AF motor failure risk is real. Always test the AF thoroughly before buying. Listen for any grinding or hesitation. The Sigma 50mm f/1.4 Art is a better lens in every measurable way but larger and heavier. If the AF motor works, this remains a capable and compact 50mm.