Pentax 28-50mm F/3.5-4.5 SMC M 2-Touch K Mount Manual Focus Lens

The Pentax 28-50mm F/3.5-4.5 SMC M 2-Touch K Mount Manual Focus Lens is a compact, manual-focus wide-to-standard zoom lens introduced in 1979 for Pentax’s K-mount 35mm film SLR cameras, part of the second-generation “M-series” lineup designed to complement small, lightweight bodies like the Pentax ME and MX. It’s a practical, travel-friendly lens covering wide-angle through standard perspectives in a single, compact package.

Optically, the lens covers a 28-50mm focal range with a variable maximum aperture of f/3.5 at the wide end narrowing to f/4.5 at full telephoto, down to a minimum of f/22. The 10-element, 10-group optical design delivers good resolution and contrast across the entire zoom range, even wide open, and is finished with Pentax’s Super Multi Coating (SMC), reducing flare and improving contrast and color rendition. A 6-blade automatic diaphragm contributes to the lens’s background rendering.

The lens uses a two-touch (two-ring) design, giving independent control over focal length and focus via separate zoom and focus rings. As a fully manual lens, both focus and aperture are controlled directly on the lens barrel, with an aperture ring lacking the “A” (Auto) setting found on later Pentax-A lenses, meaning the lens works with aperture-priority metering but not with cameras capable of programmed autoexposure.

Build quality is a solid, all-metal construction, consistent with Pentax’s M-series lenses, which were engineered to be roughly 20% lighter and shorter than their standard SMC counterparts while maintaining the same build quality, resolution, and durability. The lens has a minimum focusing distance of approximately 0.6m (2 ft.), measures approximately 65 x 52mm, and weighs approximately 310-328g. It accepts a 52mm filter thread.

As a full-frame-compatible K-mount lens, the Pentax 28-50mm F/3.5-4.5 SMC M delivers its full 75.4°-46.8° diagonal angle of view on full-frame 35mm film or digital Pentax K-mount bodies, and an effective, narrower field of view on Pentax’s APS-C format digital SLR cameras.

Key Features
– 28-50mm standard zoom (SMC Pentax-M) for Pentax K mount
– Maximum aperture f/3.5-4.5 (variable)
– 10 elements in 10 groups optical construction
– Super Multi Coating (SMC)
– 6-blade automatic diaphragm
– Two-touch (two-ring) zoom and focus design
– Fully manual focus and aperture control (no “A” aperture setting)
– All-metal construction
– Minimum focusing distance of approximately 0.6m (2 ft.)
– 52mm filter thread
– Approximate weight: 310-328g
– Compatible with Pentax K-mount 35mm film and APS-C digital SLR cameras