Pentax 50-135mm f/2.8 SMC PENTAX-DA* ED IF SDM Autofocus APS-C Lens for K-Mount Review

The Pentax 50-135mm f/2.8 SMC PENTAX-DA* ED IF SDM is a fast telephoto zoom designed for Pentax K-mount APS-C bodies, offering a useful 77-205mm full-frame equivalent range. As part of Pentax's Star series, it features Extra-low Dispersion glass to minimize chromatic aberration, a Supersonic Drive Motor for quieter autofocus, and a constant f/2.8 aperture that provides solid low-light performance and shallow depth-of-field control. The lens is built with internal focusing to maintain length during zoom and focus operations.

At $251 on the used market, this lens represents an affordable entry into fast telephoto zooms for Pentax shooters. It fills a natural gap between standard zooms and longer primes, making it a versatile option for portraits, events, and sports. The Star designation suggests premium build quality and optical design, though real-world performance and autofocus reliability will vary with age and condition. Pentax users seeking a dedicated telephoto zoom with a bright aperture will find this lens fits a classic niche in the APS-C lineup.