This extreme 650-1300mm f/8-16 Manual Focus Lens from Bower is an economical way to achieve some ultra-telephoto photography, all the way up to 1300mm.  This is a T-mount lens, which means that aperture is not communicated to or controlled by the camera body, and in this particular configuration is delivered with a T-mount which fits any "M42" system camera, also known as the Pentax screw mount.

It has only one effective aperture at any focal length, which varies from f/8.0 at 650mm to f/16.0 at 1300mm.  That's not much of a hinderance, however, as you'd likely use this lens at its relatively small maximum aperture in any case.  Only use this lens in fully manual mode.

This lens requires bright light and high-ISO film to get a fast shutter speed, and needs a sturdy tripod or monopod, but can deliver very sharp results if used properly.

Incredible zoom range

Multi-coated elements reduce flare and increase light transmission

White barrel helps reduce heat buildup

Aperture is fixed-position, but only varies based on focal length

Deep lens shade with matted, dark internal coloring

Tripod mount upon lens barrel