see also:

• Nikon F dSLR system

• this rare super telephoto lens was 1st introduced in 1970 and is a catadioptric mirror lens, and as with all such mirror lenses, share the following characteristics:
  • manual focus
  • fixed aperture (in this case f/11)
  • 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
• Nikon stopped making mirror lenses in 2005

• 2000mm focal length and field of view (1.2°) at infinity focus
• fixed f/11 aperture (a 10“ f/10 telescope in astronomic terms)
• 5 elements in 5 groups
• closest focus 18m
• no lens hood
• rear built-in filters
• 262mm diam x 598mm long and 17.5kg

• http://www.mir.com.my/rb/photography/companies/nikon/nikkoresources/reflex/1000mm.htm