Pentax (Takumar) Pentax Takumar 55mm f1.8 Heritage

Overview

The Takumar 55mm f/1.8 was produced by the Asahi Optical Co. (later known as Pentax, now a subsidiary of Ricoh) in Japan. Asahi Optical was founded by Kumao Kajiwara, who named the Takumar line after his brother, the painter Takuma Kajiwara. According to the reviews, the lens existed in multiple M42 screw-mount variants produced from 1958 to 1975, all sharing the same 6-element/5-group optical formula. It began as the simple 'Takumar 55mm F1.8' in the late 1950s, evolving through Auto-Takumar, Super-Takumar, Super-Multi-Coated (S-M-C) Takumar, and finally SMC Takumar versions, and was frequently bundled with cameras like the Asahi Pentax SV and the Spotmatic. The Super-Takumar 55mm f/1.8 specifically was released in 1962 as a set lens for the Pentax SV. The reviews note it is often called 'radioactive' because at least one glass element (from the 1965 version onward) uses thorium glass, which yellows over time — a yellowing that can be reduced by exposing the lens to ultraviolet light (sunlight). It enjoys a cult following partly because of its extreme affordability, solid build, pleasing rendering, and vintage character. One reviewer notes it is arguably the most popular vintage lens in Japan today, ranking just behind the Helios 44-2 in Instagram popularity, and is widely recommended for beginners entering vintage lens photography. No coined nickname beyond the descriptive 'radioactive' is evidenced in these reviews.

Verdict: The Takumar 55mm f/1.8 is one of the best-value entry points into vintage lens photography. Inexpensive, superbly built, and full of character, it delivers beautiful bokeh and a charming nostalgic flare that make it beloved among beginners and enthusiasts alike — especially in Japan, where it ranks among the most popular vintage lenses. It's not sharp wide open and struggles with bright light, but stopped down to f/2-f/2.8 it produces lovely results. Ideal for anyone wanting an affordable, characterful standard prime for portraits, low-light, and film shooting, provided they accept its vintage quirks like softness wide open and possible thorium yellowing.

Optical Character

Bokeh

Beautiful, pleasing bokeh that renders busy backgrounds smoothly, though slightly less creamy than an f/1.4 lens.

Color

Unknown, though thorium-glass versions commonly develop a yellow cast reducible with UV exposure.

Sharpness wide open

Not very sharp wide open with bluish fringing and softer corners, improving noticeably stopped down to f/2 or f/2.8.

Flare resistance

Flares readily with a nostalgic, photogenic character; struggles with bright light even with a hood.

Contrast

Prone to reduced contrast in bright light and backlit conditions.

Community Insights

What people love

Beautiful, pleasing bokeh that renders busy backgrounds smoothly
Nostalgic, photogenic flare that gives images a vintage feel
Excellent build quality with smooth focus and aperture rings, even on aged copies; metal lens cap gives a high-class feel
Very affordable (average around $40) making it an ideal entry point into vintage lenses
Compact and lightweight (around 39mm long, ~200g)
Works especially well on film according to one reviewer
Highly recommended for beginners wanting to try vintage glass

What people dislike

Not sharp wide open at f/1.8 and shows bluish color fringing
Struggles with bright light and backlighting, losing contrast even with a hood
Corners are noticeably softer than the center
Thorium-glass versions yellow over time and require UV treatment
M42 screw mount can unscrew when closing the aperture if the mount isn't properly locked
f/1.8 doesn't provide the creamier look or low-light advantage of faster f/1.4 lenses

Pro Tips

Stop down to f/2 or f/2.8 for noticeably sharper results and less color fringing than wide open
Avoid facing the sun directly to preserve contrast, or embrace the flare intentionally for a nostalgic look
Use a lens hood in bright conditions, though be aware flare can still appear
If the yellowing bothers you, expose the lens to UV light/sunlight to reduce it
Always secure the M42 screw mount before use so it doesn't unscrew when closing the aperture
Try it on film for what one reviewer feels is its best rendering
Use the correct adapter for your camera (M42-PK for Pentax DSLRs, M42-NEX for Sony mirrorless)

Sources (1)

Web-grounded synthesissecondary

The Takumar 55mm f/1.8 was produced by the Asahi Optical Co. (later known as Pentax, now a subsidiary of Ricoh) in Japan. Asahi Optical was founded by Kumao Kajiwara, who named the Takumar line after his brother, the painter Takuma Kajiwara. According to the reviews, the lens existed in multiple M42 screw-mount variants produced from 1958 to 1975, all sharing the same 6-element/5-group optical formula. It began as the simple 'Takumar 55mm F1.8' in the late 1950s, evolving through Auto-Takumar, Super-Takumar, Super-Multi-Coated (S-M-C) Takumar, and finally SMC Takumar versions, and was frequently bundled with cameras like the Asahi Pentax SV and the Spotmatic. The Super-Takumar 55mm f/1.8 specifically was released in 1962 as a set lens for the Pentax SV. The reviews note it is often called 'radioactive' because at least one glass element (from the 1965 version onward) uses thorium glass, which yellows over time — a yellowing that can be reduced by exposing the lens to ultraviolet light (sunlight). It enjoys a cult following partly because of its extreme affordability, solid build, pleasing rendering, and vintage character. One reviewer notes it is arguably the most popular vintage lens in Japan today, ranking just behind the Helios 44-2 in Instagram popularity, and is widely recommended for beginners entering vintage lens photography. No coined nickname beyond the descriptive 'radioactive' is evidenced in these reviews.

https://overland25.com/en/en_vintagelens/super-takumar-55mm-f18https://www.pentaxforums.com/lensreviews/SMC-S-M-C-Super-Auto-Takumar-55mm-F1.8.htmlhttps://www.myfavouritelens.com/super-takumar-55mm-f1-8/https://jerfareza.camera/post/lens-review-asahi-pentax-takumar-55mm-f1-8