The SMC Pentax-M 28mm f/2.8 is a compact manual-focus wide-angle prime lens for Pentax K-mount 35mm and full-frame digital SLRs, produced in two versions between 1977 and 1984. Both versions share a 7-element/7-group optical design, a 5-blade automatic diaphragm, and Pentax’s Super Multi-Coating (SMC) for improved contrast and flare resistance. The second version adopted the optical formula of the later A-series lens and dropped the silver decorative ring, but both deliver similar performance. With a 75° diagonal field of view on full-frame and a minimum focus distance of 0.3m, it’s well-suited for landscapes, street photography, and general-purpose shooting. The lens uses a 49mm filter thread, weighs around 156–170g, and measures just 63 × 31mm, making it a great choice for lightweight kits. While it lacks an “A” setting on the aperture ring, it’s fully compatible with manual and aperture-priority modes on Pentax DSLRs. Optically, it performs best from f/5.6 to f/11, with decent center sharpness and moderate contrast. Wide open, it’s a bit soft with some corner softness and lower contrast, but stopping down improves clarity significantly. Its rendering has a slightly vintage character, and while the bokeh isn’t its strong suit, it’s a solid performer for its size and price.

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Release Date: 1977
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