Vivitar Series 1 450mm f/4.5 Asph Solid Cat mirror lens

introduction

this super telephoto lens introduced in the mid 1980's is a catadioptric mirror lens, and as with all such mirror lenses, share the following characteristics:
- manual focus
- fixed aperture (in this case f/4.5)
- 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
different design to the earlier Vivitar Series 1 600mm f/8 Solid Cat mirror lens and Vivitar Series 1 800mm f/11 Solid Cat mirror lens
their ruggedness is partially due to their solid, one-piece construction, unlike most production mirror lenses

450mm focal length and field of view (5.6°) at infinity focus
fixed f/4.5 aperture
11 lens elements, 7 groups - unusual use of aspherical plastic elements in its design
97mm front filter
closest focus 3.65m
35.5mm rear filter thread
T2 lens mount thread
117mm diameter, 152mm long and 1.64kg
cost ~$US800 in 1986