Sony 500mm f/8 Relex Lens

A Unique Pocket-Sized Super Telephoto

The history of catadioptic reflex telephoto mirror lenses is a long and honorable one. They are quite different from regular telephoto optics and telescopes in design in that they feature two internal mirrors that fold the light path, making such lenses much smaller and therefore lighter than a regular lens of a given focal length would be.

These have been around for telescopic use for ages, and 500mm to 1000mm versions have been made by various companies for SLRs since at least the 1960's. Nikon in particular was a proponent of these lenses for several decades.
By about the 1980's though these lenses fell out of favour and big honking super-telephotos became the norm, along with big honking prices and considerable bulk. Fast super-telephoto 500mm, 600mm and longer lenses are the wet dreams of many sports and wildlife photographers, and I have written numerous reviews of them for this site, including the Canon 500mm and 600mm lens some years ago...