Data sheet: SMC Takumar (Pentax) 50 mm f/1.4

Pekka Buttler, 06/2023


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

Brand:Asahi Opt.Co. (Pentax)Lens nameSMC Takumar 1:1,4/50
Focal length(s)150 mmAngle-of-view247 °
Maximum Aperturef/1.4In Production1972–1975
Lens mountsm42Subfamily (if applicable)––
Length341,6 mmDiameter461,6 mm
Filter ring diameter49 mmWeight253 grams
Lens element count7Lens group count6
Aperture blades (S/R/C)58 SFocus throw200 °
Minimum focusing distance45 cmsMaximum magnification1:6,9
Has manual aperture ringYESHas Manual focus ringYES

Further notes:
• This lens is part of a long and highly distinguished lineup of lenses, starting in 1964 continuing even today. See version history below.
• My sample is radioactive. If you’re unsure what that means, read this.

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.

The development of the early Takumar lenses can be summarised as:
1952–1957: ‘Takumar‘ lenses using a 37 mm thread mount (the ‘Asahiflex mount’). Typically Preset aperture lenses.
1957–1959: ‘Takumar‘ lenses using the m42 mount, mostly offering the same lenses as earlier in m37 mount.
1959–1962: ‘Auto-Takumar‘ lenses using the m42 mount, now with automatic aperture stop-down (pin in m42 mount base), but that you need to ‘cock’ after shooting to open the aperture again.
1962–1971: ‘Super-Takumar‘, as Auto-Takumar lenses, except that 1) you do not need to cock the lens after shooting; 2) Offering a switch to select between automatic and manual aperture; 3) all lenses coated (some even multicoated).
1971–1972: ‘Super-Multi-Coated Takumar‘, as Super Takumars, except for: 1) Added pin to allow open-aperture metering on compatible bodies; 2) All lenses multicoated.
1972– ≈late 70s: ‘SMC Takumar’, optically largely identical to earlier generation but with ergonomic adjustments (including rubberised focus)

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).

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).

History of the 50 mm f/1.4

The 50 mm f/1.4 lens has a very special significance to Asahi/Pentax. At the end of the 1950s Asahi/Pentax already was a successful camera company, but back then Japanese products were still often considered to be budget options and poor copies of American (in the case of e.g. cars) or German (in the case of optical equipment) products. Japanese companies were seen very similarly as we only recently viewed Chinese companies: only able to emulate, not to innovate.

This was also back when really bright (brighter than f/1.8) standard lenses on SLRs were still quite rare and often struggled mightily. Such lenses typically were forced be a bit longer than standard (> 50 mm) and often also were only limitedly usable wide open. The lens designers at Asahi set their sights on showcasing Japanese innovation prowess by doing what companies such as Zeiss and Leica had theretofore failed to do: design and produce a 50 mm f/1.4 lens that one would use wide open happily.

This goal they did achieve in the form of the 8-element 50 mm f/1.4 Super-Takumar (1964) – a lens that employed an extra element, turning the customary double-Gauss doublet group into a triplet to achieve a first: A 50 mm f/1.4 SLR lens that was actually usable wide open.

This original 8-element design has since garnered a number of nicknames, most of which are variations on ‘Planar killer’ (in reference to the Carl Zeiss Planar 55 mm f/1.4 – the lens to beat). While an undoubtable tour-de-force of Japanese lens design and manufacture, the lens was so hideously difficult and expensive (rare-earth elements in glass mixtures, large cemented triplet) to manufacture that Asahi/Pentax lost money on each lens they sold. in 1965 Asahi managed to come up with a lens of similar optical prowess, but using one lens element less, while (most importantly) being far less expensive to manufacture.

Today, that early 8 element Super Takumar has a near-mythical status among legacy lens aficionados. However, the subsequent 7 element lenses are by no means bad lenses (and some even consider them better). Importantly, the 7-element design was the one Asahi/Pentax decided was the way to go, and even the current 50 mm f/1.4 Pentax-FA uses fundamentally the same design. It is therefore fair to say that the fast fifty has been even more central to Pentax as a company than it has to other camera companies.


The genealogy of the m42 mount Takumars (the 50 mm f/1.4 included) is unusually convoluted, in part because Asahi/Pentax was in the habit of continuous design, meaning that production did not wait for a major redesign to implement modifications. This has lead to that the investigation/study into Asahi/Pentax lenses of this era is known among some lens geeks as takumarology.

Nevertheless, the following generations of the m42 mount 50 mm f/1.4 Takumars can be relatively easily identified:

• 1964–1965, ‘Super Takumar’ 8e/6g, IR index to the right of f/4
• 1965–1971, ‘Super-Takumar’ 7e/6g, Product code 37800/37801/37802 (on aperture automation switch)
• 1971–1972, ‘Super-Multi-Coated’, 7e/6g, Product code 37902
• 1972–1975 ‘SMC Takumar’, 7e/6g, Product code 37908 [this lens]

In 1975 Asahi/Pentax abandoned the m42 mount for their proprietary bayonet mount, but there is a clear familiar relationship easily observable.

• 1975–1977 ‘SMC Pentax’, 7e/6g, Product code 20847 (K-type Pentax K mount)
• 1977–1984 ‘SMC Pentax-M’, 7e/6g, Product code 20867 (K-type Pentax K mount)
• 1984–1989 ‘SMC Pentax-A’, 7e/6g, Product code 20887 (KA-type Pentax K mount)
• 1987–1991 ‘SMC Pentax-F’, 7e/6g, Product code 20827 (KAF-type Pentax K mount)
• 1991–2023 ‘SMC Pentax-FA’, 7e/6g, Product code 20817 (KAF-type Pentax K mount)
• 2023– ‘HD Pentax-FA’, 7e/6g, (KAF-type Pentax K mount)
• 2023– ‘SMC Pentax-FA Classic’, 7e/6g, (KAF-type Pentax K mount)


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.


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.

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