Nikon 500mm F8 REFLEX
This is a temptingly inexpensive long lens.
It sells for so little, typically $300 used in 2010, because it is poor for photography. It is compact, lightweight and focuses close, but the Nikon Reflex-NIKKOR f/8 N (1983-2005) does this all even better.
It makes a great telescope when used with the Lens Scope Converter since it has great central definition and little chromatic aberration.
It is very well made.
This telephoto lens does it with mirrors! It is designed based on a principal developed by the Russian optical genius Maksutov for huge astronomical telescopes.
It has a clear front. It has a big mirror in the back. It also has a little mirror on the back of the clear front element.
Light comes in and bounces off the big rear mirror and is directed towards the little mirror on the front element. From there the light is bounced back to the film through a hole in the big rear mirror. This helps keep down the size.
It takes 39mm filters screwed into the rear. It also can take front-mounted 88mm filters.
It comes in a nice case and includes four 39mm filters: yellow, red, green and the useless ND, in addition to the L37 attached to the back of the lens. If someone tries to sell you one make sure to get the filters that came with it.
There are three models of 500mm Reflex:
The original 500mm f/5. This is expensive and unusual. I think it focusses with a knob on the back, but don’t trust me on this one.
This 500mm f/8 Reflex-Nikkor C. These are very common second hand, because people are always buying them and then selling them after they try them. This is the model above and about which I’m speaking.
The 500mm f/8 N Reflex-Nikkor. It is smaller than the older 500mm f/8 shown here, and focusses even closer. It has an orange band on the focus ring to show what Nikon arbitrarily considers to be a macro range.
It is poor for photography because it has:
1.) Low contrast.
2.) Uneven illumination. It has a weird hot spot in the center of the image and gets dim at the sides.
3.) Slow speed. Even though marked f/8, because of the limited transmission and the mirror in the center blocking some of the light, it really only works like f/11. This makes it too slow to allow the fast shutter speeds that its high magnification demands.
4.) Too little weight. It is so light that it is extremely sensitive to any sort of vibration. Oddly enough, it works better handheld than on a tripod because you can couple your body mass to the system to damp the vibration.
5.) No diaphragm. It is difficult to focus because it is so slow, and then there is no added depth of field to help you out because there is no stopping down.
6.) Awful Bokeh. The out-of focus highlights are very distracting donuts of light.
On the other hand, it is superb with the Lens Scope Converter for use as a telescope because it has extremely high resolution due to the total lack of chromatic aberration.
Hand held: I get swell results at 1/250 and above. I get blurred results at 1/125 and slower.