Minolta AF Reflex 500mm f/8

Originally produced by Minolta, then by Sony, the AF Reflex 500mm f/8 was a catadioptric photographic lens compatible with cameras using the Minolta A-mount and Sony A-mount lens mounts.

The Minolta/Sony Reflex 500mm lens still (2024) 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 or RF and Nikon F or Z, but all other 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 autofocus at 8.

Minolta also produced a V-mount 400 mm f/8 Reflex lens that can autofocus at 8, but only fits the APS Minolta Vectis S-1, Minolta Vectis S-100 and Minolta Dimâge RD 3000 cameras.

The mirror design does not utilize aperture blades, and thus the aperture of the lens is fixed at 8. Exposure may only be controlled by shutter speed, film or sensor sensitivity, or a slot-in neutral density filter. The lens possesses a filter holder to that avail.

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, like all mirror lenses, it can produce donut-shaped bokeh in images, due to the secondary mirror partially obstructing the front element.

Adapters for Sony E-Mount
Using this lens on a Sony E-mount camera requires an adapter such as one of the Sony LA-EA series, not all of which are compatible with all E-mount cameras or A-mount lenses. The LA-EA2, LA-EA4 and LA-EA5 adapters have the screw drive required to enable autofocus, which is however limited to select cameras for each adapter. Otherwise, the lens will be manual focus only. The latter proves a very viable solution, even despite the shallow depth of field of the long focal length.

RF ROKKOR-X manual focus version
Since 1977, i.e. before the introduction of its autofocus system, Minolta also made manual focus, SR-mount 500mm f/8 catadioptric lenses, designated RF, RF ROKKOR, and RF ROKKOR-X successively. Their optical schemes of 6 lens elements in 5 groups differ slightly between each other, and are not the same as this autofocus lens, using 7 elements. Still, it can of course be used (fully manually) on modern cameras such as Sony E-mount, but requires a different adapter type.