Pentax SMC Takumar 6×7 500mm f/5.6

The first super-telephoto Pentax built for the 6×7 system — released in the mid-1970s as a Super-Takumar / SMC Takumar 6×7 lens, predating the later ED-glass Pentax 67 telephotos by more than a decade. In 35mm-equivalent terms, 500mm on 6×7 corresponds to roughly 250mm full-frame.

Optically a conventional refractive design without ED glass — chromatic aberration is more visible at wide apertures than on the later 400mm f/4 ED and 600mm f/4 ED; stopping down to f/8 or smaller substantially improves color rendering on high-contrast edges. f/5.6 maximum aperture is dim for the focal length but typical for super-tele lenses of the period.

Mounts on the outer bayonet (Pentax 67 lenses ≥400mm use outer). Heavier and longer than its focal length suggests due to the all-refractive design without modern lightweight materials; tripod use is mandatory and a sturdy tripod plus mirror lock-up is the working configuration.