Cosinon's fast telephoto for Pentax K — the 135mm f/2.8 with good speed.
The Cosinon 135mm f/2.8 for Pentax K is a fast telephoto from Cosina's own-brand Cosinon lens line. At f/2.8, it provides useful speed at 135mm for portraits and telephoto DOF control. Cosinon lenses are Cosina's branded optics — generally decent quality from the company that manufactures Voigtlander lenses.
Cosinon quality is decent — Cosina's optical manufacturing is competent. The f/2.8 at 135mm provides useful portrait DOF. Sharpness is respectable. The Pentax K mount benefits from body SR. Build quality is functional. Better than most budget alternatives in K mount at this focal length.
Pentax K mount. Filter thread varies. Manual focus. Benefits from Pentax body SR. The f/2.8 speed at 135mm is competitive with better-known brands at this specification. Cosinon quality is above the cheapest budget alternatives. The K mount provides universal Pentax body compatibility.
Available at low prices. Check focus and optics. A decent 135mm f/2.8 from Cosina's manufacturing heritage. The f/2.8 provides useful portrait speed. Benefits from body SR. Better than Clubman and Hanimex alternatives. Good value budget portrait telephoto for K mount.