Pentax's premium APS-C constant f/2.8 standard zoom — 24-76.5mm equiv for serious Pentax shooters.
The Pentax SMC DA 16-50mm f/2.8 ED AL IF launched in 2006 as Pentax's premium constant-aperture standard zoom for APS-C DSLRs. Covering 24-76.5mm equivalent at constant f/2.8, it was the professional workhorse zoom for the Pentax K-mount system.
Optically good — sharp across the frame with well-controlled distortion. The constant f/2.8 aperture provides consistent exposure and subject separation. SMC (Super Multi Coating) controls flare. Quick-shift Focus allows instant MF override. AL (Aspherical Lens) and ED glass.
Pentax K mount with 77mm filter thread. Approximately 565g. IF (Internal Focus) design. No weather sealing on this version. Minimum focus distance 30cm. Body-driven screw AF — speed depends on body.
Available used at mid-range prices. The DA* 16-50mm f/2.8 ED AL IF SDM improved with SDM motor and weather sealing. Competes with the Sigma 17-50mm f/2.8 EX DC OS which adds stabilisation. A solid f/2.8 zoom for Pentax users.