Data sheet: Asahi Super-Takumar 28 mm f/3.5

Pekka Buttler, 02/2026

Specifications

The table below summarizes the lens’ key specifications (measurements are based on the pictured sample):

Brand:	Asahi Opt.Co. (Pentax)	Lens name	Super-Takumar 1:3.5/28
Focal length(s)1	28 mm	Angle-of-view2	75 °
Maximum Aperture	f/3.5	In Production	1962–1971 (all versions) 1966–1971 (this version)
Lens mounts	M42	Subfamily (if applicable)	––
Length3	41,7 mm	Diameter4	57,8 mm
Filter ring diameter	49 mm	Weight	209 grams
Lens element count	7	Lens group count	7
Aperture blades (S/R/C)5	5 S	Focus throw	120 °
Minimum focusing distance (measured)	43 cm	Maximum magnification (measured)	1:12,5
Has manual aperture ring	YES	Has Manual focus ring	YES
Aperture mechanism type	Auto/Manual	Aperture click stops 6	3.5•5.6•8•11-16

Further notes:
• This lens is Asahi/Pentax second iteration of the 28 mm wide-angle lens. Compared to its predecessor, it offers a new optical recipe (see versions).
• This is an auto aperture M42 lens (standard M42). Besides aperture and focus rings it offers a Manual/Auto switch to steer aperture functionality.

Versions

The table below summarises the major steps in the genealogy of Asahi/Pentax slow(er than f/2.8) 28 mm wide-angle lenses.

Years	Mount	Name / family	Focal length & max aperture	Optical design	Aperture mechanism type	filter diameter	Notes
1952–66	M42	Super-Takumar	28 mm f/3.5	7e/6g	automatic aperture with M/A switch	58 mm
1966-71	M42	Super-Takumar	28 mm f/3.5	7e/7g	automatic aperture with M/A switch	49 mm	[this lens]
1971-76	M42	Super-Multi-Coated Takumar	28 mm f/3.5	7e/7g	automatic aperture with M/A switch	49 mm
1976-77	Pentax K	smc Pentax	28 mm f/3.5	8e/7g	automatic aperture	52 mm
1977–85	Pentax K	smc Pentax-M	28 mm f/3.5	6e/6g	automatic aperture	49 mm

History of Asahi / Pentax

The camera business today known Pentax was founded in 1919 as Asahi Kogaku Kogyo (Asahi Optical Company). Initially the company manufactured lenses for eyeglasses, later diversifying into projection lenses and even later into photographic lenses, supplying lenses for camera makers such as Konishiroku (Konica) and Molta (Minolta) and binoculars.

In 1952 – the year of the Helsinki olympiad – Asahi released the Asahiflex, the first Japanese 35 mm SLR. Together with its SLR cameras, Asahi introduced a line of lenses that carried the name ‘Takumar’, in honour of the founder’s brother.

In 1975 Asahi/Pentax introduced its own bayonet mount – The Pentax K mount – and phased out the production of m42 lenses and cameras. The name Takumar would remain on Pentax lenses until 1979 (and made some sporadic reappearances). The Pentax K mount is still a current mount, but it has several versions/generations. For details, see the JAPB article on the Pentax K mount.

Pentax was among the handful of Japanese camera manufacturers to keep up with the introduction of autofocus SLR cameras, and even survived the shift from film SLRs to digital SLRs (albeit somewhat struggling).

Adapting

If you want to natively mount this lens you need to find a functioning m42 mount film camera. Luckily that should be relatively easy as m42 bodies were produced in their millions and most of them lack features that are especially likely to have deteriorated to the point of making the entire camera inoperable.

Adapting this lens to a mirrorless, full-frame digital camera is a breeze thanks to the lens having full manual controls (aperture ring, focus ring). You simply need a dumb adapter from m42 to your mirrorless system (And set the lens in manual mode to be sure the aperture works as you intend).

Due to the medium flange focal distance used by the m42 mount (45,46 mm), whether you can adapt this lens to dSLR/SLR mounts depends on which dSLR mount: Canon EF, Four Thirds, Minolta/Sony A and Pentax K can mount m42 lenses using a simple adapter ring. Nikon F on the other hand is not as problem-free, and – to retain anything near infinity focus – the adapter will necessitate corrective optics. In all cases, your camera will work only in stop-down metering.

Footnotes

1. Focal length is (unless stated otherwise) given in absolute terms, and not in Full-frame equivalent. For an understanding of whether the lens is wide/tele, see ‘Angle-of-view’. ↩︎
2. Picture angle is given in degrees (based on manufacturers’ specs) and concerns the diagonal picture angle. Rule of thumb:
   > 90 ° ==> Ultra-wide-angle
   70–90 ° ==> Wide-angle
   50–70 ° ==> Moderate wide-angle
   40–50 ° ==> ‘Standard’ or ‘normal’ lens
   20–40 ° ==> Short tele lens
   10-20 ° ==> Tele lens
   5-10 ° ==> Long tele lens
   < 5 ° ==> Ultra-tele lens ↩︎
3. Length is given from the mount flange to the front of lens at infinity. ↩︎
4. Diameter excludes protrusions such as rabbit ears or stop-down levers. ↩︎
5. S=straight; R=rounded; C=(almost)circular at all apertures. ↩︎
6. Numbers equal aperture values on aperture ring; • intermediate click; – no intermediate click. ↩︎