Pentax's premium APS-C telephoto — DA* constant f/2.8 from 75-202.5mm equiv with SDM motor.
The Pentax SMC DA* 50-135mm f/2.8 ED SDM launched in 2007 as Pentax's premium constant f/2.8 telephoto zoom for APS-C. The DA* designation indicates Pentax's highest optical tier. SDM (Supersonic Drive Motor) provides in-lens AF.
Optically very good — DA* quality with constant f/2.8 across 75-202.5mm equivalent. ED glass for chromatic aberration control. SDM motor for quieter, faster AF than body-driven alternatives. Weather-resistant construction.
Pentax K mount with 67mm filter thread. Approximately 685g. Weather-resistant construction. SDM motor. Quick-shift Focus System. 100cm minimum focus distance. The DA* telephoto for the Pentax APS-C system.
Available used at mid-range prices. The only constant f/2.8 telephoto for Pentax APS-C below the D FA 70-200mm f/2.8. SDM motors had reliability issues on some units — check AF operation. For serious Pentax APS-C portrait and event photographers.