Sigma 35-70mm f/2.8-4 — faster-than-usual manual-focus standard zoom from the early 1980s.
Sigma's 35-70mm f/2.8-4 was a faster-than-usual manual-focus standard zoom from the early-to-mid 1980s, aimed at photographers wanting more speed than typical kit zooms of the period without stepping up to a fixed 35mm or 50mm prime.
The lens runs 35-70mm with a variable f/2.8-4 maximum aperture, a one-touch zoom and manual focus action, and a metal barrel typical of Sigma's manual-era construction. It was produced in numerous mounts, including M42, Pentax K, Canon FD, Nikon F, Minolta MD, Olympus OM, Konica AR and Contax/Yashica.
The relatively fast aperture for its class gives a brighter viewfinder image and more depth-of-field control than slower kit zooms, with reasonably contrasty rendering once stopped down to f/5.6 or beyond.
Being a compact and useful standard zoom, it is a common secondhand find. Check the zoom and focus rings move without grinding, verify the aperture ring clicks are firm, and inspect for internal haze from long storage.