===== Pentax-A 645 SMC 55mm f/2.8 =====
{{ :lens:pentax-a645smc55mmf2.8.png?300|}}
==== Summary ====
The SMC Pentax-A 645 55mm f/2.8 is a manual-focus wide-angle prime introduced in 1984 for the Pentax 645 medium format system, designed to deliver a field of view equivalent to about 35mm on full-frame. It was one of the original lenses launched with the 645 system and remains a popular choice for both film and digital shooters thanks to its compact size, fast aperture, and classic Pentax rendering. Optically, it features an 8-element, 7-group design with Super Multi-Coating (SMC) and an 8-blade automatic diaphragm, stopping down to f/22. The lens focuses as close as 45cm, offering a 0.17× magnification ratio, and uses a 58mm filter thread. It weighs 410g, measures 74 × 60.5mm, and includes a manual aperture ring with an “A” setting, enabling full automation on compatible bodies. There’s no internal focusing or weather sealing. A screw-in RH-B hood and S80-80 soft case were typically bundled.
==== Tech Specs ====
| Manufacturer |Pentax|
| Series |Pentax-A|
| Model |645 SMC|
| Focal Length |55mm|
| Max Aperture |f/2.8|
| Min Aperture |f/22|
| Format |645 film|
| Image Circle |-|
| Minimum Focus |45cm|
| Focus Rotation |°|
| Iris Blades |8|
| Optical Design |8/7|
| Squeeze |none|
| Front Diameter |74mm|
| Filter Thread |58mm|
| Focus/Zoom Rod |none|
| Native Mount |Pentax 645|
| Data Protocol |none|
| Length |60.5mm|
| Weight |410g|
| Body Telescope |-|
| Body Material |-|
| Focus Drive |-|
| Iris Drive |-|
| Zoom Drive |-|
==== History ====
Country of Origin: \\
Release Date: \\
Launch Price: \\
Design Revisions: \\
==== Service ====
Service Manual: (Insert link to manual here) \\
\\
Full CLA: **TBD hrs.**\\
\\
==== Cine-Mod ====
Focus Ring O.D.: -\\
Zoom Ring O.D.: -\\
Iris Ring O.D.: -\\
De-click Y/N: -\\
Additional Notes: \\
==== Notes ====
==== Media ====