see also:

• super telephoto mirror lenses

• 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

• 350mm focal length and field of view (7.3°) at infinity focus
• fixed f/5.6 aperture
• 7 lens elements, 4 groups (BBAR multicoated)
• closest focus 1.1m giving 1:2.5 macro
• 82mm filter thread + 30.5 mm rear filter
• 86mm diameter, 79mm long and 577g
• adaptall II lens mount

• apparently not a very sharp lens
• http://www.adaptall-2.org/lenses/06B.html