The Bower 500mm f/8 Manual Focus Lens is a classic refractor-style T-mount lens, with an aperture diaphragm in the middle of the lens body to stop down the aperture when necessary.  However, it is assumed that much of the shooting with such a lens will be at its maximum f/8.0 aperture, with a tripod, monopod, or other such support.

This super telephoto works on both "full frame" cameras as well as the "APS-C" style digital SLR cameras. The 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 only.

This lens' sophisticated achromatic refractor design yields images with pleasing peak contrast and well controlled flare.  It can be used at maximum aperture on a very bright day for some images of moving subjects.

This lens can also be used as a handheld telescope by adding Lumicon's LA1070 adapter along with a 1.25" 45°/60°/90° diagonal and any 1.25" eyepiece, or for astrophotography by using on an SLR mounted to a Vixen GP2 Photo Guider or other motorized equatorial telescope mount.