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photo:samyang800mmf8

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Samyang 800mm f/8 mirror lens

introduction

  • NB. these lenses are often branded Rokinon, Opteka, Pro Optic, Vivitar, Bower, Walimex, Albinar, Falcon
  • 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

specs

  • 800mm focal length and field of view (3°) at infinity focus
  • fixed f/8.0 aperture
  • 8 elements / 8 groups (multicoated)
  • closest focus 3.5m
  • 105mm filter thread but mount turns when you focus + 30.5mm rear filter
  • 111mm diameter, 145mm long and 946g
  • T2 camera mount
  • kit comes with a practical transport bag, T2 adapter for the selected system and protective caps.
  • ~$190

reviews

    • “reputation for being impossible to focus, and blurry to the point that there is no micro contrast”
    • post shows how he made a geared focus microtuner and a rotating (off-set) aperture to address some of these issues
  • if outside temperature is 20F degrees below inside, you need to let the lens cool for 30 min or so before it is usable.
photo/samyang800mmf8.txt · Last modified: 2014/05/17 09:21 by gary1