Tamron SP 500mm f/8.0 BBAR mirror lens

see also:

• super telephoto mirror lenses

• this super telephoto lens introduced in 1983 (discontinued in 2005) 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 in 4 groups (BBAR multicoated)
• closest focus 1.7m which gives 1:3 macro
• 82mm filter thread non-rotating
• 30.5mm rear filter
• 84mm diameter, 92mm long and 595g
• Adaptall II camera mount
• NB. there was an earlier model called 55B which did have some optical problems due to mirror design. All that was optimized in the 55BB model

• photozone.de review on a Nikon DX camera:
  • minimal pincushion distortion, minimal vignetting (0.4EV), good sharpness, minimal CA
  • for reasonably sharp results you either need a very sturdy tripod or extremely fast shutter speeds (1/750sec or faster)
  • “Unless you want to have a lens for “emergency” use you should probably better consider conventional tele lenses”
• Bob Atkins - Tamron 500mm f/8 vs Canon 500mm f/4.5L