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Sigma 500mm f/4 Ultratel mirror lens


  • this super telephoto lens introduced in ? is a catadioptric mirror lens, and as with all such mirror lenses, share the following characteristics:
    • manual focus
    • fixed aperture (in this case f/4)
    • 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/4 aperture
  • lens elements, ? groups
  • closest focus 15m (3m via an extension tube)
  • rear filter thread
  • T lens mount thread
  • 159mm diameter, 216mm long and 2.7kg (6lb)
  • comes with a special lens cap that has a removable inner section. Leaving the lens cap in place, but removing the inner section, cuts the mirror's aperture to f/5.6
  • matching 2X teleconverter


photo/sigma500mmf4.txt · Last modified: 2014/05/18 18:17 by gary1

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