===== Pentax-A SMC 28-135mm f/4 ===== 
{{ :lens:pentax-a_smc_28-135mm_f4.png?350|}}
==== Summary ====
The SMC Pentax-A 28–135mm f/4 is a manual-focus, full-frame zoom lens introduced in 1984 and produced until 1991, designed for K-mount film SLRs. It was one of the few Pentax zooms of the era to offer a constant f/4 aperture across its range, and it was positioned as a premium all-in-one solution for travel, landscape, and general-purpose photography. Optically, it features a 17-element - 15-group design with Super Multi-Coating (SMC) and a 6-blade automatic diaphragm. The lens stops down to f/22, focuses as close as 1.7 meters, and delivers a 0.33× magnification ratio—with a macro mode at 28mm that enables closer focusing for near-life-size detail. It uses a 77mm filter thread, weighs a hefty 820g, and measures 80 × 112mm. The lens includes a manual aperture ring with “A” setting, a rotating front element, and was typically sold with the RH-A80 hood and HE-169 hard case. It lacks internal focusing or weather sealing.
==== Tech Specs ====
| Manufacturer    |Pentax|
| Series          |A Series Zoom|
| Model           |SMC|
| Focal Length    |28-135mm|
| Max Aperture    |f/4|
| Min Aperture    |f/22|
| Format          |Full-Frame|
| Image Circle    |-|
| Minimum Focus   |170cm|
| Focus Rotation  |°|
| Iris Blades     |6|
| Optical Design  |17/15|
| Squeeze         |none|
| Front Diameter  |80mm|
| Filter Thread   |77mm|
| Focus/Zoom Rod  |none|
| Native Mount    |Pentax K|
| Data Protocol   |none|
| Length          |112mm|
| Weight          |820g|
| Body Telescope  |-|
| Body Material   |-|
| Focus Drive     |-|
| Iris Drive      |-|
| Zoom Drive      |-|
==== History ====
Country of Origin:  \\
Release Date: 1984 \\
Launch Price:  \\
Design Revisions:  \\

==== 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 ====
<nodisp 8>
Focus Ring O.D.: -\\
Zoom Ring O.D.: -\\
Iris Ring O.D.: -\\
De-click Y/N: -\\
Additional Notes: \\
</nodisp>
==== Notes ====
==== Media ====