Cosinon's telephoto zoom for Pentax — the 80-200mm f/4.5 in PKM mount.
The Cosinon 80-200mm f/4.5 for Pentax PKM is a telephoto zoom from Cosina's Cosinon brand. The PKM designation indicates Pentax K mount with M-series manual coupling — no auto-aperture on program modes. The constant f/4.5 provides consistent exposure. Cosinon quality is decent from Cosina's manufacturing heritage.
Cosinon quality — decent from Cosina manufacturing. Constant f/4.5 is a modest advantage. The 80-200mm covers standard telephoto. The PKM coupling means stop-down metering on digital Pentax bodies — less convenient than PKA auto-aperture. Benefits from Pentax body SR stabilisation. Build quality functional.
Pentax K mount, PKM designation — M-series coupling. Manual focus. Stop-down metering on digital bodies. Benefits from body SR. The PKM designation limits auto-exposure convenience versus PKA versions. Constant f/4.5. Better K-mount telephoto options exist with auto-aperture coupling.
Very cheap. The PKM coupling limits convenience — PKA versions preferred. Constant f/4.5 is a modest advantage. Decent Cosinon quality. Not recommended when auto-aperture alternatives exist. Only at near-zero prices for K-mount users who understand stop-down metering.