===== Pentax-A 645 SMC 45-85mm f/4.5 ===== 
{{ :lens:pentax-a645smc45-85mmf4.5.png?250|}}
==== Summary ====
The SMC Pentax-A 645 45–85mm f/4.5 is a manual-focus standard zoom introduced in the mid-1980s for the Pentax 645 medium format system. Covering a focal range equivalent to approximately 35–66mm in 35mm terms, it was designed to replace three primes—45mm, 55mm, and 75mm—in a single, versatile package. It shares its optical formula with the later FA version but retains full manual focus and aperture control, with an “A” setting for Program and Shutter-Priority automation on compatible bodies. Optically, it features an 11-element - 9-group design with Super Multi-Coating (SMC) and an 8-blade automatic diaphragm. The lens stops down to f/32, focuses as close as 50cm, and delivers a 0.22× magnification ratio—making it surprisingly capable for close-up work. It uses a 77mm filter thread, weighs 805g, and measures 79 × 99mm. It lacks internal focusing or weather sealing, but includes a manual aperture ring, a dedicated RH-RD77 screw-in hood, and was typically sold with a clip-on cap and soft case.
==== Tech Specs ====
| Manufacturer    |Pentax|
| Series          |Pentax-A|
| Model           |645 SMC|
| Focal Length    |45-85mm|
| Max Aperture    |f/4.5|
| Min Aperture    |f/32|
| Format          |645 film|
| Image Circle    |-|
| Minimum Focus   |50cm|
| Focus Rotation  |°|
| Iris Blades     |8|
| Optical Design  |11/9|
| Squeeze         |none|
| Front Diameter  |79mm|
| Filter Thread   |77mm|
| Focus/Zoom Rod  |none|
| Native Mount    |Pentax 645|
| Data Protocol   |none|
| Length          |99mm|
| Weight          |805g|
| Body Telescope  |-|
| Body Material   |-|
| Focus Drive     |-|
| Iris Drive      |-|
| Zoom Drive      |-|
==== History ====
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==== Service ====
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Service Manual: (Insert link to manual here) \\
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Full CLA: **TBD hrs.**\\
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==== Cine-Mod ====
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Focus Ring O.D.: -\\
Zoom Ring O.D.: -\\
Iris Ring O.D.: -\\
De-click Y/N: -\\
Additional Notes: \\
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==== Notes ====
==== Media ====