MC Rubinar 500mm f/8 Reflex

an all-manual mirror lens (also known as reflex lens, catadioptric lens, CAT)

in addition to this there appears to be 500 mm f/5.6 and 1000 mm f/10 CATs available

estimated retail price 350 USD

in my use from 3/2006 to 10/2008

only for outdoor use on bright days and is still hard to focus

much cheaper, smaller and lighter than the equivalent focal length regular lenses

if you need a 500 mm lens and don't have much money there are no alternatives

ring-shaped bokeh can be fun

every photographer should try a mirror lens once

weak contrast

not very sharp

requires plenty of light to be usable and is still hard to focus (I recommend a body with a large bright viewfinder and installing manual focusing screen like Canon Ec-S)

fixed aperture (f/8)

ring-shaped bokeh can be annoying