Pentax SMC Pentax-A 50mm f/1.7

NormalMount: Pentax K50mmf/1.7 – f/22
Introduced: 1983

SMC Pentax-A 50mm f/1.7 is the A-series successor to the SMC Pentax-M 50mm f/1.7 — the "A" designation indicates automatic aperture coupling that enables full Program AE and Shutter-Priority AE on the Pentax A3000, ZX-series, and later AF bodies. The optical formula is similar to the M-series sibling but with refined coatings and the A-mount aperture-coupling mechanism.

Key features

  • 50mm focal length on 35mm full-frame
  • f/1.7 maximum aperture
  • 49mm filter thread
  • Pentax K-A bayonet — automatic aperture coupling for full AE on compatible bodies
  • 6-element design with refined SMC coating

Use case + rendering

  • Standard prime with full AE compatibility on Pentax bodies that support A-coupling
  • Sharp wide-open at center; very sharp by f/2.8

Compatible bodies

  • All Pentax K-mount cameras work mechanically: K1000, MX, ME Super, LX
  • Full Program AE on Pentax A3000, ZX, MZ, *ist series, and digital K-mount bodies

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