Pentax 645 mount was developed by Pentax in the early 1980s, and released in 1984 with Pentax 645 camera. It is a bayonet mount with three tabs, made for medium format film, with a focal flange distance of 70.87mm and a throat diameter of 61.2mm. Mount supports electric and digital communication, film, and digital sensors with an aspect ratio of 4:3, for a 6×4.5cm film format. The aperture is controlled mechanically, with a lens clutch. Focus can be achieved manually, as well as automatically – mount supports screw-drive and digital focus control with lenses with built-in focus motors. There is support for in-lens stabilization.
There are three film bodies and two digital bodies. Film bodies include the original, manual focus 645, and later, 645N and 645N II, both with support for autofocus and FA 645-series lenses. Digital bodies are the original 645D with a 40mpx Kodak CCD sensor, and the later 645Z with a 51mpx Sony CMOS sensor, both 44×33mm in size.
Compared to the usual 35mm format, the crop factor of Pentax 645 mount lenses is 0.62 for film-era full-frame lenses, and 0.79 for digital bodies with 44×33mm sensors.
Pentax-A 645 lenses
A 645 series lenses are manual focus, auto-aperture lenses, the functional equivalent of Pentax K-mount A series lenses.
- smc Pentax-A 645 35mm F3.5 ~21mm-equivalent
- smc Pentax-A 645 45mm F2.8 28mm-equivalent
- smc Pentax-A 645 Zoom 45–85mm F4.5 ~28–50mm-equivalent
- smc Pentax-A 645 55mm F2.8 ~35mm-equivalent
- smc Pentax-A 645 75mm F2.8 ~45mm-equivalent
- smc Pentax-A 645 Zoom 80–160mm F4.5 50–100mm-equivalent
- smc Pentax-A 645 Macro 120mm F4 75mm-equivalent
- smc Pentax-A 645 150mm F3.5 ~95mm-equivalent
- smc Pentax-A 645 200mm F4 ~125mm-equivalent
- smc Pentax-A★ 645 300mm F4 ED [IF] ~185mm-equivalent
- smc Pentax-A★ 645 600mm F5.6 ED [IF] ~370mm-equivalent
Leaf shutter lenses
Lenses labelled as LS have leaf shutters built-in, using flash with those lenses is possible for all speeds of their shutters, up to 1/500s. LS lenses are missing an A setting on the aperture ring, preventing the camera to use Program and Shutter priority modes.
- smc Pentax 645 LS 75mm F2.8 ~45mm-equivalent
- smc Pentax 645 LS 135mm F4 ~85mm-equivalent
Pentax-FA 645 lenses
FA 645 series lenses support screw-drive driven autofocus, they are the functional equivalent of Pentax K-mount FA series lenses.
- smc Pentax-FA 645 Zoom 33–55mm F4.5 AL ~20–35mm-equivalent
- smc Pentax-FA 645 35mm F3.5 AL [IF] ~21mm-equivalent
- smc Pentax-FA 645 45mm F2.8 ~45mm-equivalent
- smc Pentax-FA 645 Zoom 45–85mm F4.5 ~28–50mm-equivalent
- smc Pentax-FA 645 Zoom 55–110mm F5.6 ~35–70mm-equivalent
- smc Pentax-FA 645 Zoom 80–160mm F4.5 50–100mm-equivalent
- smc Pentax-FA 645 Macro 120mm F4 75mm-equivalent
- smc Pentax-FA 645 150mm F2.8 [IF] ~95mm-equivalent
- smc Pentax-FA 645 Zoom 150–300mm F5.6 ED [IF] ~95–185mm-equivalent
- smc Pentax-FA 645 200mm F4 ED ~125mm-equivalent
- smc Pentax-FA 645 300mm F5.6 ED [IF] ~185mm-equivalent
- smc Pentax-FA★ 645 300mm F4 ED [IF] ~185mm-equivalent
- smc Pentax-FA 645 400mm F5.6 ED [IF] ~250mm-equivalent
Pentax-D FA 645 and DA 645 lenses
The latest series of lenses are optimised from the ground up for digital sensors. While most of the lenses fully cover a 6×4.5cm film frame, leading to D FA 645 designation, two of the lenses carry the DA 645 designation, meaning their image circle covers only the smaller size of the sensor.
- smc Pentax-D FA 645 25mm F4 AL SDM AW [IF] ~20mm-equivalent
- smc Pentax-DA 645 25mm F4 AL SDM AW [IF] ~20mm-equivalent
- HD Pentax-DA 645 Zoom 28-45mm F4.5 ED AW SR ~22-35mm-equivalent
- HD Pentax-D FA 645 35mm F3.5 AL [IF] ~28mm-equivalent
- smc Pentax-D FA 55mm F2.8 AL SDM AW [IF] ~45mm-equivalent
- HD Pentax-D FA 645 Macro 90mm F2.8 ED AW SR ~70mm-equivalent
- Pentax 645 Lenses on Wikipedia
- Pentax 645 on Camera-Wiki
- Pentax 645Z Special site on Ricoh-Imaging.co.jp
- Lens mount list on Wikipedia
Last update 05.12.2022.