The SMC Pentax-M 120mm f/2.8 is a compact manual-focus telephoto prime introduced in 1977 as part of the second-generation M-series for the Pentax K-mount. It replaced the earlier K-series 120mm f/2.8, offering a lighter, more compact design while retaining the same focal length and optical formula. With its slightly unusual focal length, it sits between the more common 100mm and 135mm lenses, making it a distinctive choice for portraiture, travel, and compressed landscape scenes. Optically, the lens features a 5-element, 5-group design with Super Multi-Coating (SMC) and an 8-blade automatic diaphragm, stopping down to f/32. It focuses as close as 1.2 meters, delivers a 0.13× magnification ratio, and uses a 49mm filter thread. The lens weighs just 270g, measures 63 × 63mm, and includes a built-in slide-out hood—a hallmark of M-series telephotos. There’s no internal focusing or “A” setting on the aperture ring, so metering on modern digital bodies requires stop-down operation.

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Release Date: 1977
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