Lets review mirror and lenses tele-photo objective lens Rokinon 500M-AI 500mm F8.0 Mirror Lens. Judging by its view and description, it looks like telescope with Maksutov-Kassegrene scheme and for attachment to camera it uses astronomical device – Т-adapter ( these adapters are available for all cameras mounts types ). It has fixed 500 mm focus, fixed f/8 aperture ( it is not very light by photo lenses standards ), 1.7 m minimal focusing distance and 35 mm maximal optical sensor size. Lens does not support auto-focusing and there is need to perform it manually. It has 7 optical elements in 6 groups; there is ability to attach 72 mm optical filters to its frontal side, on the back side it has 30.5 mm thread for smaller optical filters ( 3 of optical devices of this type are included in package of lens ). Photo lens sizes are : 86 ( diameter ) x 100 ( length ) mm, weight is : 363 g. Package contains : Rokinon 500M-AI 500mm F8.0 Mirror Lens itself; optical filters ND-2X, ND-4X and Skylight; frontal and rear caps; carrying and storage pouch; and user’s guide. It is supplied with 1 year warranty of manufacturer. This is very good tele-photo lens, which can be used for land-based shooting of distant objects and for astronomical objects shooting, and its price is quite adequate in comparison with other tele-photo lenses. There is even ability to invent something and add telescope eyepieces to it and use it as stars gazing device. Its minuses include : small aperture by photo-lenses standards, but f/8 aperture is average for telescopes; also lack of zoom, variable diaphragm and auto-focusing can cause difficulties for novice photographers or in videos recording, but it has small optical elements amount and this reduces light dispersion, internal reflections and increases light strength of lens, so, experienced photographers will be able to make very good photos with it.