Pentax's classic M42 telephoto prime — the radioactive thorium-glass Takumar with legendary rendering.
The Pentax Asahi Super-Takumar 135mm f/2.5 is a manual focus telephoto prime in the universal M42 screw mount. Part of the revered Super-Takumar lineup from the 1960s and 1970s, it offers a fast f/2.5 aperture at 135mm — faster than most competitors of the era. The Super-Takumar series is widely regarded as producing some of the finest optics of the film era.
Optical performance is very good with a distinctive character. Sharpness is excellent from f/2.5, making it genuinely usable wide open for portraits. The rendering has a warm, pleasing quality that vintage lens enthusiasts prize. Bokeh is smooth at wider apertures. Some versions use thorium oxide glass elements that develop a yellow tint over time, correctable by UV exposure.
M42 screw mount — the universal mount that adapts to virtually every modern camera system via simple threaded adapters. Filter thread is 49mm. Weight is approximately 395 grams. Build quality is superb with precision all-metal construction and a beautifully smooth helicoid focus ring. The aperture ring clicks at half-stop intervals.
Common on the used market given the enormous production numbers. Check for radioactive yellowing in the glass — hold the lens up to a light source to check for amber tint. Also check for haze and fungus. An outstanding portrait lens that adapts to any mirrorless camera. The M42 mount makes it one of the most versatile vintage lenses available.