Sony/Minolta's A-mount 20mm — budget wide-angle with body-driven AF for the Alpha system.
The Sony 20mm f/2.8 (SAL20F28) is an A-mount wide-angle prime inherited from the Minolta AF 20mm f/2.8. It provides 20mm ultra-wide coverage on full-frame Sony Alpha DSLRs with body-driven screw autofocus.
Optically adequate — sharp from f/5.6. The 20mm provides useful ultra-wide perspectives. Body-driven screw AF. No in-lens stabilisation — relies on body SteadyShot. Full-frame coverage.
Sony A-mount with 72mm filter thread. Approximately 285g — compact. Full-frame coverage. Body-driven AF. No weather sealing. Minimum focus distance approximately 25cm.
Available used very cheaply. A-mount is discontinued. The 72mm filter thread seems large for the lens size. For existing A-mount owners needing budget ultra-wide coverage. Check for smooth focus operation.