Sigma's pre-Art 50mm f/1.4 — the earlier version that was good but the Art replaced it dramatically.
The Sigma 50mm f/1.4 EX DG HSM launched in 2008 as Sigma's premium 50mm prime before the Art lineup transformed the brand. It offered f/1.4 speed with HSM autofocus at a competitive price against Canon and Nikon's own 50mm f/1.4 lenses.
Optically good — sharper than Canon's 50mm f/1.4 USM at the time with pleasant bokeh. HSM motor is fast and quiet. The EX designation indicates professional build quality. Some field curvature and focus shift when stopping down — not unusual for fast 50mm designs.
Available for multiple mounts. 77mm filter thread — large for a 50mm. Approximately 505g. No weather sealing. Full-frame coverage. Minimum focus distance 45cm. 9 rounded aperture blades.
Available used very cheaply. The Sigma 50mm f/1.4 DG HSM Art replaced it and is dramatically sharper — one of the most important lens upgrades in photography. The EX version is only worth considering at bargain prices. Check for AF accuracy — use USB dock if available.