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 SDM (Star series) was released in 2007 as the professional constant f/2.8 standard zoom for Pentax K-mount APS-C, covering 24.5-76.5mm equivalent. Fifteen elements in 12 groups including ED and aspherical elements. Nine aperture blades. 77mm filter thread. At 565g. 0.30m MFD. SDM (Supersonic Drive Motor) in-lens.
The optical design uses 15 elements in 12 groups (2 ED + 3 aspherical elements; SMC coating). Nine aperture blades. The 77mm filter thread. At 565g the lens is moderate. Minimum focus distance of 0.30m (0.21× maximum magnification). SDM (Supersonic Drive Motor) for quiet AF. f/2.8 constant aperture. Star (★) series designation. APS-C image circle. Pentax K-mount.
The DA★ Star designation is Pentax's premium tier: the SDM motor provides quiet, fast autofocus suited to video and environmental portrait photography. The constant f/2.8 aperture through the full 16-50mm range enables consistent exposure during zoom transitions. The 77mm filter thread reflects the optical demands of full-aperture coverage at 16mm.
On the used market the Pentax DA★ 16-50mm f/2.8 SDM is affordable as a Pentax premium standard zoom. Condition checks: SDM AF response, 77mm front element for marks, zoom ring smoothness. APS-C only. Compatible with Pentax K-mount APS-C bodies.