|Prominar lenses, in Shashin Kōgyō July 1957. (Image rights)|
Kowa made a few Prominar interchangeable lenses, to mount on cameras made by other makers. The lenses directly sold by Kowa, released in mid 1957, were the 35mm f/2.8 and 100mm f/2 in Leica screw mount, and the 200mm f/2.8, initially for Leica or Exakta, and later for other SLR cameras. Different lenses were supplied to Allied Impex to mount on the Miranda SLR cameras.
Announcements and other documents
The Prominar interchangeable lenses were announced in the July 1957 issue of Shashin Kōgyō. The column mentions the 35mm f/2.8 and 100mm f/2 in Leica screw mount, and the 200mm f/2.8 with manual diaphragm, either in Leica screw mount with reflex housing or in Exakta mount. The same lenses are also listed in the table of interchangeable lenses in the next issue of Shashin Kōgyō, dated Summer 1957, with the price mentioned as "not fixed yet" (未定).
|First announcement, in Shashin Kōgyō July 1957. (Image rights)|
The lenses were probably not immediately available, and another announcement appeared in the November 1958 issue of Shashin Kōgyō. It describes the 35mm f/2.8 and 100mm f/2 for Leica, respectively priced at ¥13,000 and ¥24,500 (with finder and leather case), and a new preset version of the 200mm f/2.8, available at ¥49,500 in Pentax or Exakta mount. The two longer lenses were still listed in the July 1959 issue of the same magazine, in an article on tele lenses.
|Second announcement, in Shashin Kōgyō November 1958. (Image rights)|
Prominar 35mm f/2.8
The Prominar 35mm f/2.8 has six elements in four groups, with a Gauss formula. Its optical design is probably the same as on the fixed lens of the Kallowide and Kallowide F. (Other 35mm f/2.8 lenses made by Kowa are the Prominar wide angle lens of the Kallo 140 and Kowa 140 rangefinder cameras with leaf shutter, which may have the same optical design, and a lens for leaf-shuttered SLR cameras, which probably differs.)
The front and rear part of the lens barrel have a very different styling, giving a rather disparaged aspect. The rear mount and focusing ring are chrome plated, with a tab and an infinity lock. The distance scale is engraved in feet, going down to 3.5ft. The lens head is black, and has a massive aperture ring with knurls and chrome stripes. (A similar styling is found on the Kallo 140 lens, but the knurled ring is used for focusing on the latter.) The ring has click stops, and is normally graduated from 2.8 to 22, though the first announcement in July 1957 reported f/16 minimum aperture only. The front bezel is engraved Prominar 1:2.8 f=35mm Kowa Optical Works Japan No.xxxxxxx. The filter thread has 34mm diameter and 0.5mm pitch, and the lens can also take 36mm diameter push-on accessories. The length is 34mm (with cap), and the weight is 150g.
The lens is very uncommon, and the only serial numbers confirmed so far are 1600072 and 1600290. Similar numbers in the 16xxxxx range are known on the other Prominar 35mm f/2.8 lenses, on the Kallowide, Kallowide F and for the Kallo 140 and Kowa 140.
The lens was sold in a red and blue presentation box, inscribed PROMINAR LENS on the lid and PROMINAR LENS f2.8 F=35mm on the side, containing the lens and external viewfinder (see below). The lens cap is all chrome with the name Prominar engraved.
The external viewfinder has a black and chrome finish. Its external aspect is quite similar to the auxiliary Kontur-like finders offered by Kowa for its rangefinder cameras. The viewfinder's barrel is a black cylinder, with a chrome front rim inscribed Prominar and 35mm, and a chrome ring at the rear, graduated in feet from ∞ to 3.5ft, for manual parallax compensation.
Prominar 100mm f/2
|Prominar 100mm f/2 for Leica, with external finder. From Shashin Kōgyō November 1958. (Image rights)|
The Prominar 100mm f/2 in Leica mount is very little known, and no other still camera lens made by Kowa has the same characteristics. At the same period, other 100mm f/2 lenses were offered by Fuji and Zunow.
The optical design has six elements in three groups, and a Sonnar formula. The barrel is predominantly black, with chrome front and rear ends, and large chrome stripes on the knurled focus ring. The July 1957 announcement reported 3.5ft minimum distance, but the lens actually sold in 1958–9 focused down to 5ft only. The aperture ring is all black, and reportedly goes to f/32 with click stops. The front rim is chrome coloured. The filter thread has 55mm diameter and 0.75mm pitch, and the external diameter for push-on accessories is 57mm. The bezel is engraved Prominar 1:2 f=100mm Kowa Optical Works Japan No.xxxxxx. The barrel has 64.5mm diameter and 90mm length, and weighs 740g.
The lens cap is black, with the name Prominar inscribed in white or silver letters. It seems that a dedicated lens hood was supplied. It is slipped outside the lens rim and held by a tightening screw. The viewfinder has the same aspect as that for the 35mm lens.
The lens is extremely uncommon, and the only serial number confirmed so far is 220112.
Prominar 200mm f/2.8
|Manual Prominar 200mm f/2.8, in Leica or Exakta mount. From Shashin Kōgyō Summer 1957. (Image rights)|
The manual version, announced in Summer 1957, has the same finish as the 100mm f/2. The aperture ring goes to f/32 with unevenly spaced click stops. The minimum distance is 8ft. The filter thread has 77mm diameter (0.75mm pitch) and the external diameter for push-on accessories is 80mm.
|Preset Prominar 200mm f/2.8, in Pentax or Exakta mount. From Shashin Kōgyō November 1958. (Image rights)|
The lens was announced in Exakta mount or in Leica screw mount. The latter was apparently made for use with a reflex housing, perhaps the Visoflex I. No surviving example of the manual version has been observed yet, and it is not known if it was effectively sold. The pictures reproduced in this page seems to show a serial number beginning with "170", perhaps in the 170xxxx range.
The preset version, released in Autumn 1958, has a similar barrel but for the black front end. The two aperture rings have evenly spaced click stops, on every third-stop from 2.8 to 32. The minimum distance is either 8ft or 2.5m, apparently corresponding to two distinct variations.
The lens was initially announced in 42mm screw mount and Exakta mount, and the Leica-mount version was apparently dropped. The dimensions are 90.5×150.5mm in Pentax mount, and 90.5×152mm in Exakta mount, and the weight is respectively 1600 and 1495g. Actual examples are also known in Nikon F mount.
- Column in Shashin Kōgyō July 1957, p.79.
- The column in Shashin Kōgyō July 1957, p.79, actually has "for Leica mount and Exakta mount, with reflex housing" (ライカマウント及びエキザクタマウントレフボックス付), presumably meaning Leica mount with reflex housing or Exakta mount.
- Table in Shashin Kōgyō Summer 1957, p.109.
- Column in Shashin Kōgyō November 1958, p.569.
- Table of available tele lenses in Shashin Kōgyō July 1959, p.54.
- The lens sold as lot no.391 of Westlicht auction no.14 has aperture stops to 22.
- Example no.1600072 pictured in Awano, p.124 of Kurashikku Kamera Senka no.32; example no.1600290 sold as lot no.391 of Westlicht auction no.14 (November 30, 2008).
- Pictures observed on a Japanese forum.
- Picture of the preset Nikon F version in this page at Red Book Nikkor.
- Miyazaki Yōji (宮崎洋司). Yomigaeru ka, M42 maunto renzu no sekai o yuku: Kokusan kamera mēkā to M42 renzu (よみがえるか、M42マウントレンズの世界をゆく：国産カメラメーカーとM42レンズ). In Shashin Kōgyō (写真工業) April 2003. Pp.47–56. (Mentions the Prominar 200mm f/2.8 in 42mm screw mount.)
- Shashin Kōgyō no.62, July 1957. "News Flash". P.79.
- Shashin Kōgyō no.63, Summer 1957. "Nihon no kamera zenbō: Kōkan renzu ichiran" (日本のカメラ全貌・交換レンズ一らん, Compendium of Japanese cameras: Table of interchangeable lenses). Pp.108–9.
- Shashin Kōgyō no.79, November 1958. "News Flash". P.569.
- Shashin Kōgyō no.87, July 1959. "Kokusan bōen renzu ichiran-hyō" (国産望遠レンズ一覧表, Table of Japanese tele lenses). P.54.
- Pictures taken with a Prominar 35mm f/2.8 at Ishi no ue ni mo 30-nen
- Picture taken with a Prominar 100mm f/2 on an Epson R-D1s at Camera Hiking