Originally produced by Minolta, and until recently, produced by Sony, the AF Reflex 500mm f/8 is a catadioptric photographic lens compatible with cameras using the Minolta A-mount and Sony A-mount lens mounts.
The Minolta/Sony Reflex 500mm lens is the only production mirror lens designed to auto focus with an SLR camera. There are other mirror lenses that can mount onto current mounts such as Canon EF-mount and Nikon F-mount, but all of these mirror lenses are manual focus only. Only this lens can have its focus controlled by the camera's autofocus motor in conjunction with TTL autofocus sensing. In terms of the Minolta AF and subsequent Sony α SLR systems, this lens is an anomaly, being the only lens guaranteed to auto focus at f/8. Minolta also produced a V-mount 400 mm f/8 Reflex lens that can autofocus at f/8, but only the Minolta Vectis S-1, Minolta Vectis S-100 and Minolta Dimâge RD 3000 can use it.
The mirror design does not utilize aperture blades, and thus the aperture of the lens is fixed at f/8. Exposure may only be controlled by shutter speed, film or sensor sensitivity, or a rear-mounted neutral density filter.
By using a mirror design similar to that of a telescope, this lens uses very little glass compared to traditional telephoto lenses and is thus much smaller, lighter, and far less expensive than traditional lenses in the same focal length. However, this and all other mirror lenses, can produce a donut-shaped bokeh in the image it produces, which is usually undesirable.
Minolta 500mm Reflex Lens
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