Pentax's compact M-series wide prime — a manual-focus 28mm f/3.5 with Super Multi Coating.
The SMC Pentax-M 28mm f/3.5 is a compact wide-angle prime for the Pentax K bayonet mount, from the M-series generation built to be small and light alongside Pentax's downsized MX and ME bodies. The 28mm was a staple wide lens for everyday shooting.
This is a manual-focus lens with a 28mm focal length and a maximum aperture of f/3.5, carrying Pentax's Super Multi Coating. The M line prioritised compactness, so the barrel is short; confirm the filter thread and other details on the specific lens rather than assuming.
A 28mm gives a moderate wide field that renders naturally with only mild distortion, well suited to street, travel, landscape and general use. The f/3.5 aperture keeps the lens small and light while still covering most everyday conditions.
M-series 28mm primes are common and affordable, making them popular first vintage lenses for adapting. Check the glass for haze and fungus, confirm the aperture blades are dry and quick, and test the focus ring for smooth movement. It mounts on Pentax K digital bodies and adapts easily to mirrorless.