Pentax SMC Pentax 67 55-100mm f/4.5

One of two zoom lenses in the Pentax 67 system (the other being the 90-180mm f/5.6) — the wide-to-normal zoom covering the range from the 55mm f/4 wide through approximately the 105mm f/2.4 normal position.

A constant-aperture f/4.5 zoom — slower than the prime equivalents at the same focal lengths, but offering the framing flexibility of a zoom on a system otherwise dominated by primes. In 35mm-equivalent terms, 55-100mm on 6×7 corresponds roughly to 27-50mm full-frame, covering the wide-through-normal range typical for landscape, environmental portraits, and reportage.

Released during the 1989 Pentax 67 redesign era. Optically competent but not as sharp as the prime-lens line at any single focal length — the typical zoom-vs-prime tradeoff. Useful primarily as a kit-reduction tool for travel or location work where carrying multiple wide-to-normal primes is impractical. Mounts on the inner bayonet; 67mm filter thread.