Pentax's FA telephoto — the 80-200mm f/4.7-5.6 with program mode for digital use.
The Pentax FA 80-200mm f/4.7-5.6 is the FA-version upgrade of the F 80-200mm — adding program-mode auto-aperture compatibility for Pentax digital bodies. Same slow variable aperture. The FA designation adds the A-position on the aperture ring for auto-exposure in all camera modes including program. Benefits from body SR.
Same basic optics as the F version with the FA auto-aperture advantage for digital Pentax bodies. The A-position enables program auto-exposure and all auto modes on digital Pentax. Benefits from body SR. The very slow f/4.7-5.6 remains the main limitation. SMC coating. A modest upgrade over the F version for digital use.
Pentax K mount, full-frame (FA). Filter thread varies. Weight varies. Build quality basic with FA aperture ring. The FA designation is the key upgrade over the F version — enabling full auto-exposure on digital Pentax bodies. Screw-drive AF. Benefits from body SR. The slow aperture limits practical utility.
Very cheap. The FA designation adds digital convenience over the F version. Benefits from body SR. Still very slow aperture. Better K-mount telephoto options exist. The FA auto-aperture is the sole advantage over the F version at similar near-zero pricing.