see also:

• super telephoto mirror lenses

• this super telephoto lens introduced in 2010?? is a catadioptric mirror lens, and as with all such mirror lenses, share the following characteristics:
  • manual focus
  • fixed aperture (in this case f/8.0)
  • 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

• 500mm focal length and field of view (5°) at infinity focus
• fixed f/8.0 aperture
• 7 elements / 6 groups (multicoated)
• closest focus 1.7m which gives 1:2.7 macro
• 72mm filter thread but mount turns when you focus + 30.5mm rear filter
• supplied with 30.5mm Skylight, ND2, and ND4 filters as well as front and rear lens caps and a soft lens pouch
• 77mm diameter, 88mm long and 320g
• T2 camera mount
• Samyang website