see also:

• super telephoto mirror lenses

• this Russian made super telephoto lens introduced in ? is a modified Maksutov catadioptric mirror lens, and as with all such mirror lenses, share the following characteristics:
  • manual focus
  • fixed aperture (in this case f/4.5)
  • 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

• 300mm focal length and field of view (8.3°) at infinity focus
• fixed f/4.5 aperture
• lens elements, ? groups
• closest focus m
• M116 rear filter thread
• M42 lens mount thread
• mm diameter, mm long and kg