Overview

The Pentax smc DA* 50-135mm F2.8 ED (IF) SDM is a weather-sealed, constant-aperture telephoto zoom for APS-C, offering solid optical performance with excellent MTF results and minimal chromatic aberration. However, wide-open sharpness at 70mm and f/22 across the range can be weak. Build quality is high with weather sealing and smooth rings, though the zoom ring placement may hinder handling. Autofocus via SDM is quiet and responsive. It suits portrait and mid-range action photographers, but its high cost may lead some to consider the cheaper 55-300mm alternative.