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photo:minolta250mmreflex

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Minolta Rokkor RF 250mm f/5.6 mirror lens

introduction

  • this is a very popular and now expensive mirror lens
  • this super telephoto lens introduced in 1979 is a catadioptric mirror lens, and as with all such mirror lenses, share the following characteristics:
    • manual focus
    • fixed aperture (in this case f/5.6)
    • virtual elimination of chromatic aberration as uses mirror rather than lenses
      • also means focus position for infrared photography is the same as for light photography
    • central mirror:
      • allows much more compact lens length as the optic path is reflected internally twice
      • by necessity, blocks some of the light and thus causes:
        • decrease in image contrast
        • characteristic “doughnut” shaped bokeh imagery in out of focus areas

specs

  • 250mm focal length and field of view (10° ??) at infinity focus
  • fixed f/5.6 aperture
  • 6 lens elements, 5 groups (multicoated)
  • closest focus 2.5m (8.2')
  • 62mm filter thread but mount turns when you focus + 39 mm rear filter
  • 68mm diameter, 71mm long and 262g
  • Ebay prices tend to be $600-1200

reviews

photo/minolta250mmreflex.txt · Last modified: 2014/05/17 12:34 by gary1