Canon's early full-frame wide zoom with USM, a compact wide-angle from the EOS film era.
The Canon EF 20-35mm f/3.5-4.5 USM is one of Canon's earliest ultra-wide zooms, launched in 1993. Covering 20-35mm on full-frame, it provided affordable wide-angle capability in a remarkably compact and lightweight package for the EOS film system.
Optical quality is acceptable for the era with adequate centre sharpness but soft corners on full-frame, particularly at 20mm. Ring USM provides fast silent AF. Build is compact and lightweight at just 340g.
Canon EF mount, 77mm filter thread. This has been thoroughly superseded by the EF 17-40mm f/4L, EF 16-35mm f/2.8L, and RF wide zooms. The 20mm starting point is not as wide as modern 16mm alternatives.
Very cheap used. Check USM motor and zoom ring. The lens is primarily of historical interest. Any modern Canon wide zoom is dramatically better. Only justified at near-zero prices for casual wide-angle shooting.