Minolta AF 500mm Reflex lens

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Key features
Minolta 500mm f/8 Reflex
Maker:	Minolta, Sony
Ultrasonic motor:	No
Macro capable:	No
Unique features:	AF capable Mirror Lens
Application:	Telephoto
Technical data
Type:	Special Prime
Focal length:	500mm
Aperture (max/min):	f/8 fixed
Construction:	5 groups / 7 elements
# Diaphragm blades:	No blades, circular
Close focus distance:	4 m
Max. magnification:	1/7.7
Physical
Max. length:	118 mm
Weight:	665 g
Filter diameter:	Front 82mm & Rear drop-in (Clear and NDx4)
Accessories
Lens hood:	Front threaded
Angle of view
Horizontal:	4.9°
History
Introduced:	1991
Replaced by:	Minolta version succeeded by Sony version in 2006
Retail info
MSRP US$	$699 USD - Sony Version

Originally produced by Minolta, and currently produced by Sony, the AF 500mm Reflex, is a catadioptric photographic lens compatible with cameras using the Minolta AF and Sony α lens mounts.

The Minolta/Sony 500mm Reflex 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 able to auto focus at f/8 (with the exception of this lens, all other AF lenses must be f/5.6 or larger for AF to function).

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 an undesirable donut shaped bokeh in the image it produces.