Pentax's compact M-series wide zoom — a manual-focus 28-50mm f/3.5-4.5.
The SMC Pentax-M 28-50mm f/3.5-4.5 is a compact wide-to-standard zoom for the Pentax K bayonet mount, from the M-series generation designed to be small and light to match Pentax's downsized bodies. It offered a modest wide range in a single manageable lens.
This is a manual-focus lens with a 28-50mm zoom range and a variable maximum aperture of f/3.5 at the wide end and f/4.5 at 50mm. It carries Super Multi Coating. Exact construction and filter thread should be confirmed against the specific sample rather than assumed.
The 28-50mm span runs from a moderate wide angle to a short standard, useful for landscapes, street scenes, travel and everyday shooting where a compact zoom is preferred over carrying separate primes. The variable aperture keeps the barrel short.
Early M-series zooms are affordable and pleasant to adapt because of their size, though they are slower than the primes. Check the zoom and focus action for smoothness, inspect for haze, dust and fungus, and confirm the aperture blades are dry. It fits Pentax K digital bodies and adapts to mirrorless with an adapter.