The Bower 500mm f/8.0 Manual Focus Lens is a catadioptric mirror T-mount lens, precision manufactured in South Korea.  It is delivered in this configuration with a T-mount adapter to fit the Nikon F system cameras.

When combined with the T-mount, this mirror lens mounts to any Nikon F-mount camera and works on both FX "full frame" cameras as well as the "APS-C" style DX digital SLR cameras.  However, the fixed f/8 aperture is not communicated to the camera body.  As such, you can use the lens in "M" manual exposure mode, or "A" aperture-priority mode upon certain cameras.

Despite this lens' long 500mm focal length, it has a compact 3 x 3.5" size and weighs under 1 pound, making it a bit easier to handle than normal 500mm refractor lenses (it should be used with a tripod or monopod in any case).  It also has a much different rendering of out of focus areas than a normal lens; highlights will be doughnut-shaped rings with more saturation and contrast on the edge of the ring than on the center.

This lens is an ideal candidate for astrophotography use when mounted to a Vixen GP2 Photo Guider (or other motorized equatorial telescope mount).

Fixed-aperture 500mm f/8 mirror lens

Multicoated optics

Distinct out-of-focus highlight characterization

Excellent close focusing capacity

Accepts 30.5mm filters at rear of lens barrel

Made in South Korea