Data sheet: Yashica DSB 50 mm f/1.9 (C/Y)

Pekka Buttler, 11/2024

Specifications

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

Brand:	Yashica	Lens name	DSB 50mm 1:1.9
Focal length(s)1	50 mm	Angle-of-view2	46 °
Maximum Aperture	f/1.9	In Production	1976–3
Lens mounts	Contax/Yashica	Subfamily (if applicable)	––
Length4	39,5 mm	Diameter5	63,0 mm
Filter ring diameter	52 mm	Weight	193 grams
Lens element count	6	Lens group count	4
Aperture blades (S/R/C)6	6 S	Focus throw	180 °
Minimum focusing distance	50 cms	Maximum magnification	1:7,9
Has manual aperture ring	YES	Has Manual focus ring	YES
Aperture mechanism type:	Auto	Aperture click stops:7	1.9-2.8-4-5.6-8-11-16

Further notes:
• In the Contax/Yashica era Yashica lenses were divided into three series:
• ML (abbreviation of Multi-Layer, in reference to coating technology). Yashica’s premium line of lenses. Designed and manufactured by Yashica.
• DSB (abbreviation unclear). Yashica’s budget line. Not premium coatings. Not designed or manufactured by Yashica.
• YUS (Yashica US). Yashica’s budget line for the Americas. Not premium coatings. Not designed or manufactured by Yashica.

• The Yashica DSB 50 mm f/1.9 was originally introduced as the entry-level kit lens for the Yashica FX-2 in 1976.
• Throughout the life of the Contax/Yashica system, Yashica offered a broad range of fifties in both the ML line as well as the budget DSB line, including:
• ML 55 mm f/1.2 (7 elements in 6 groups)
• ML 50 mm f/1.4 (7 elements in 6 groups)
• ML 50 mm f/1.7 (6 elements in 5 groups)
• ML 50 mm f/1.9 (6 elements in 5 groups)
• DSB 50 mm f/1.9 (6 elements in 4 groups), [this lens]
• ML 50 mm f/2 (6 elements in 4 groups)
• DSB 55 mm f/2 (6 elements in 4 groups)
• Yashica offered a series of square-formatted clamp-on lens hoods for its primes, but as they are very rare today, it seems they did not come supplied with the lenses. If you need a lens hood for your lens, you can try a generic 52 mm thread lens hood for standard lenses.

Versions

I have no information of a significant redesign having happened during the life of this lens. There are – however – some visible differences:
– looking at online samples it is quite clear that while some lenses were manufactured to have ‘silver rings’ (i.e. no black paint on the leading edge of the filter threads and focus ring; like in the picture above), other lenses lack this feature. I have yet to find a logic to this design choice as it is not congruent with serial number progression
– at the time when going from 7-digit serial numbers to 8-digit serial numbers, the mount-end’s construction was changed. Especially this relates to the prong used to communicate the lens’ maximum aperture which changed from a moulded pin to a metal bracket mounted (and adjustable) using screws (see image below)

Adapting

This lens cannot be used natively on any current SLR or dSLRs. To use it in its native environment, you will need a Contax or Yashica body with a Contax/Yashica mount. Luckily these are quite easy to find, and Yashica’s manufacture of the electronics has been relatively resilient to the teeth of time. (The same cannot be said for the leatherette’s used on Contax/Yashica bodies, and the light seals quite often need fixing, but those are minor issues…)

Thanks to being a fully manual lens (manual aperture, manual focus), the lens can be adapted to all mirrorless cameras using a suitable adapter. Moreover, a simple ‘dumb adapter’ will do the job perfectly. Thanks to the popularity of the C/Y mount, the availability of adapters to all mirrorless mounts can be taken for granted, on the other hand, specialist adapters (speed boosters, helicoid adapters, tilt/shift adapters) are not available for all mirrorless mounts, but daisy-chaining adapters (e.g. C/Y->Canon EF; Canon EF –> mirrorless) can offer a work-around.

Adapting C/Y mount lenses on dSLRs can also be an option, depending on which dSLR.
• Canon EF has the shortest flange focal distance among full-frame dSLR’s and Canon’s wide range of dSLRs are able to mount C/Y lenses perfectly using a simple adapter ring.
• Sony/Minolta A, Pentax K and Nikon F dSLRs are not able to use C/Y lenses without an adapter that uses corrective optics to allow infinity focus. However, such adapters are readily available.

History of the Contax/Yashica system

The Contax/Yashica system as well as the eponymous mount were co-designed by Zeiss and Yashica under the aegis of “Top Secret Project 130”. Zeiss’ intended contribution to the co-operation was the name ‘Contax’ as well as lens designs and the manufacturing of some of the lenses whereas Yashica would take care of camera manufacturing as well as some lens manufacturing. Moreover – beside the line of premium ‘Contax’ camera bodies and Carl Zeiss lenses, Yashica could also sell Yashica-branded bodies and lenses. This co-operation gave Yashica a leg up in competing with other Japanese Camera manufacturers while also allowing Zeiss access to the kind of economies of scale⁸ it needed and could not reach by itself.

The Contax (Contax/Yashica) system was unveiled at the Photokina fair in 1974 and the Contax RTS body hit shelves in 1975. While many German pundits thought it an outrage to produce anything named Contax outside of Germany, overall reception was very favourable. Not only would the new system be able to use Zeiss’ optics, also the new body design (especially the ergonomic for which the F. Porsche design studio had been engaged) seemed very promising.

The system was initially centred on aperture priority auto exposure, and the body-lens interface did not allow for the camera body to control aperture. To facilitate shutter priority and program auto, Yashica/Contax in 1984/5 unveiled the 159MM body (MM=multi-mode) and an upgrade to existing lenses so that they would support the full range of auto exposure modes in MM-capable bodies.

While somewhat successful, the the Zeiss-Yashica co-operation was by no means unproblematic. Yashica often felt Zeiss was unwilling to commit to sufficient volume (which likely contributed to production over time increasingly shifting to Japan). Moreover, although Contax/Yashica were at the forefront of the autofocus revolution (as evidenced by the functional prototype unveiled at fotokina 1982) Zeiss killed that development trajectory by claiming AF lenses could not be manufactured to Zeiss’ standards – a move that later led to Yashica’s breakaway AF system (see some details here) as well as the only serially manufactured in-body AF system in the 1996, Contax AX (touched upon here).

While the Contax / Yashica system technically stayed alive until replaced by the less successful Contax N autofocus system, it’s clear that as autofocus took the world by storm in the late 80s, early 90s, the Contax / Yashica system devolved into a niche / aficionado solution in the early 90s.

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. While dating the beginning of production is relatively easy, the end of production is not as easy to ascertain with certainty, but likely late 1980s. ↩︎
4. Length is given from the mount flange to the front of lens at infinity. ↩︎
5. Diameter excludes protrusions such as rabbit ears or stop-down levers. ↩︎
6. S=straight; R=rounded; C=(almost)circular at all apertures. ↩︎
7. Numbers equal aperture values on aperture ring; • intermediate click; – no intermediate click. ↩︎
8. ‘economies of scale’ is a business term signifying the phenomenon where manufacturing costs per unit fall when manufacturing numbers increase. Importantly, while almost all manufacturing industries have economies of scale, some industries have stronger economies of scale than others. Also, for economies of scale to be able to realise their effect, there needs to be a sufficient demand. ↩︎