Pentax's A-series standard macro — a manual-focus 50mm f/2.8 with close focus and an 'A' setting.
The SMC Pentax-A Macro 50mm f/2.8 is a standard-length macro prime for the Pentax K bayonet mount, from the A-series generation with the 'A' aperture position for program and shutter-priority automation. It combined a normal focal length with close-focusing macro ability.
This is a manual-focus lens with a 50mm focal length and a maximum aperture of f/2.8, carrying Super Multi Coating and an 'A' setting for camera-controlled aperture. It focuses much closer than a standard 50mm; verify the exact maximum reproduction ratio and filter thread on the specific sample.
At 50mm the macro design doubles as a sharp normal prime for portraits, general shooting and video, while the close-focus capability suits flowers, small objects and product work. The moderate working distance of a 50mm macro requires getting near the subject at high magnification.
A-series macro primes are prized for their sharpness and the 'A' aperture automation on later bodies. Check the focus helicoid for smooth extension, inspect for haze and fungus, confirm the aperture is dry and the 'A' position locks, and test for any focus-ring slack. It fits Pentax K digital bodies and adapts to mirrorless.