The SMC Pentax-AF 35-70mm f/2.8 is a historically significant lens introduced in 1981 as Pentax’s first autofocus lens, designed exclusively for the Pentax ME-F—the world’s first TTL autofocus SLR. It features a constant f/2.8 aperture, a rarity at the time, and was built with an in-lens AF motor powered by four AAA batteries. On any camera other than the ME-F, it functions as a manual-focus lens, behaving much like an M-series zoom with no electronic aperture control. Optically, it employs a 7-element, 7-group design with Super Multi-Coating (SMC) and an 8-blade automatic diaphragm, stopping down to f/22. It focuses as close as 1.2 meters, uses a 58mm filter thread, and weighs 580g, measuring 73 × 77mm. The lens lacks internal focusing, quick-shift, or an “A” setting on the aperture ring, so it requires stop-down metering on modern bodies. It was typically bundled with a RH-60 slip-on hood and a dedicated hard case.

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Release Date: 1981
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