CLeW

The SMC Pentax 135mm f/3.5 (K-series) is a first-generation manual-focus telephoto lens introduced in 1975 for the Pentax K-mount system. It was part of the original wave of bayonet-mount lenses that replaced the M42 screw-mount Takumars, and it reflects that transitional era with its solid, all-metal construction and classic optical design. With a 135mm focal length and a relatively modest f/3.5 maximum aperture, it was designed as a compact, affordable option for portraiture, nature, and general telephoto use—offering reach without the bulk or cost of faster lenses. Optically, the lens employs a 4-element, 4-group design and a 6-blade automatic diaphragm, stopping down to f/32. It focuses as close as 1.5 meters and delivers a 0.11× magnification ratio. The 52mm filter thread and 365g weight make it easy to carry, and its 88mm length gives it a balanced feel on both film and digital bodies. Unlike later M-series versions, it lacks a built-in hood, but it was typically sold with a clip-on metal hood and a dedicated hard case. The engraved name on the barrel reads “SMC PENTAX 1:3.5/135,” and it was only produced for a short time—between 1975 and 1977—before being replaced by the more compact M-series version.

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Release Date: 1975
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