View source for Kowa lenses for other cameras

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| ''Prominar lenses, in {{SK}} July 1957. {{public domain Japan new}}''
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[[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 [[39mm screw lenses|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.

''(The Prominar 7.5cm f/3.5 and 7.3cm f/3.5 of the late 1940s are not signed by Kowa, and were surely manufactured by [[Sun]], see [[K.O.L. and Sun lenses in Leica screw mount]].)''

== Announcements and other documents ==
The Prominar interchangeable lenses were announced in the July 1957 issue of {{SK}}.<REF name="SK62"> Column in {{SK}} July 1957, p.79. </REF> The column mentions the 35mm f/2.8 and 100mm f/2 in [[39mm screw lenses|Leica screw mount]], and the 200mm f/2.8 with manual diaphragm, either in [[39mm screw lenses|Leica screw mount]] with reflex housing or in [[Exakta lenses|Exakta mount]].<REF name="reflex housing"> The column in {{SK}} 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. </REF> The same lenses are also listed in the table of interchangeable lenses in the next issue of {{SK}}, dated Summer 1957,<REF name="table SK63"> Table in {{SK}} Summer 1957, p.109. </REF> with the price mentioned as "not fixed yet" (未定).

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| ''First announcement, in {{SK}} July 1957. {{public domain Japan new}}''
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The lenses were probably not immediately available, and another announcement appeared in the November 1958 issue of {{SK}}.<REF name="SK79"> Column in {{SK}} November 1958, p.569. </REF> 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 [[42mm screw lenses|Pentax]] or [[Exakta lenses|Exakta mount]]. The two longer lenses were still listed in the July 1959 issue of the same magazine, in an article on tele lenses.<REF name="table SK87"> Table of available tele lenses in {{SK}} July 1959, p.54. </REF>

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| ''Second announcement, in {{SK}} November 1958. {{public domain Japan new}}''
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== Prominar 35mm f/2.8 ==
=== Description ===
The '''Prominar 35mm f/2.8''' has six elements in four groups,<REF name="SK62" /><REF name="table SK63" /> with a Gauss formula.<REF name="SK79" /> 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.<REF name="SK62" /><REF name="SK79" /> 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,<REF name="SK62" /><REF name="SK79" /> and is normally graduated from 2.8 to 22,<REF name="SK79" /><REF> The lens sold as lot no.391 of Westlicht auction no.14 (see links below) has aperture stops to 22. </REF> though the first announcement in July 1957 reported f/16 minimum aperture only.<REF name="SK62" /> 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.<REF name="SK62" /><REF name="SK79" /> The length is 34mm (with cap), and the weight is 150g.<REF name="SK79" />

=== Production ===
The lens is very uncommon, and the only serial numbers confirmed so far are 1600072 and 1600290.<REF> Example no.1600072 pictured in Awano, p.124 of {{KKS}} no.32; example no.1600290 sold as lot no.391 of Westlicht auction no.14 (November 30, 2008): see links below. </REF> 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.

=== Accessories ===
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).<REF name="pictures forum"> Pictures observed on a Japanese forum. </REF> The lens cap is all chrome with the name ''Prominar'' engraved.<REF name="pictures forum" />

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 ==
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| ''Prominar 100mm f/2 for [[39mm screw lenses|Leica]], with external finder. From {{SK}} November 1958. {{public domain Japan new}}''
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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,<REF name="SK62" /><REF name="table SK63" /><REF name="table SK87" /> and a [[Sonnar]] formula.<REF name="SK79" /> 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,<REF name="SK62" /> but the lens actually sold in 1958–9 focused down to 5ft only.<REF name="SK79" /><REF name="table SK87" /> The aperture ring is all black, and reportedly goes to f/32 with click stops.<REF name="SK62" /><REF name="SK79" /> 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.<REF name="SK62" /><REF name="SK79" /> 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.<REF name="SK79" />

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.<REF name="pictures forum" /> 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.<REF name="pictures forum" />

== Prominar 200mm f/2.8 ==
The '''Prominar 200mm f/2.8''' has five elements in four groups.<REF name="SK62" /><REF name="table SK63" /><REF name="SK79" /> Two different versions were successively announced.

=== Manual version ===
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| ''Manual Prominar 200mm f/2.8, in [[39mm screw lenses|Leica]] or [[Exakta lenses|Exakta]] mount. From {{SK}} Summer 1957. {{public domain Japan new}}''
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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.<REF name="SK62" /> The minimum distance is 8ft.<REF name="SK62" /><REF name="SK79" /> The filter thread has 77mm diameter (0.75mm pitch) and the external diameter for push-on accessories is 80mm.<REF name="SK62" /><REF name="SK79" />

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| ''Preset Prominar 200mm f/2.8, in [[42mm screw lenses|Pentax]] or [[Exakta lenses|Exakta]] mount. From {{SK}} November 1958. {{public domain Japan new}}''
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The lens was announced in [[Exakta lenses|Exakta mount]] or in [[39mm screw lenses|Leica screw mount]]. The latter was apparently made for use with a reflex housing, perhaps the [[Visoflex I]].<REF name="reflex housing" /> 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.

=== Preset version ===
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.<REF name="SK79" /> The minimum distance is either 8ft or 2.5m, apparently corresponding to two distinct variations.<REF name="SK79" />

The lens was initially announced in [[42mm screw lenses|42mm screw mount]] and [[Exakta lenses|Exakta mount]],<REF name="SK79" /><REF name="table SK87" /> 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.<REF name="SK79" /> Actual examples are also known in [[Nikon F lenses|Nikon F mount]].<REF> Picture of the preset Nikon F version in [http://redbook-jp.com/kenkyukai-e/2006/200602.html this page at Red Book Nikkor]. </REF>

{{br}}

== Notes ==
<references />

== Bibliography ==
* 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 {{SK}} (写真工業) April 2003. Pp.47–56. (Mentions the Prominar 200mm f/2.8 in 42mm screw mount.)
* {{SK}} no.62, July 1957. "News Flash". P.79.
* {{SK}} 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.
* {{SK}} no.79, November 1958. "News Flash". P.569.
* {{SK}} 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. 

== Links ==
In English:
* [https://www.leitz-auction.com/en/Kowa-Optical-Works-Prominar-2.8-35mm/AI-14-17913 Kowa Prominar 35mm f/2.8] serial no. 1600290, for Leica, with matching shoe-mounting viewfinder: lot no.391 of the [https://www.leitz-auction.com/en/Cameras/Past-Auctions/Auction-14/ fourteenth Westlicht Photographica Auction] (November 30, 2008)
In Japanese:
* [http://www5b.biglobe.ne.jp/~nikonsp/T29.html Pictures taken with a Prominar 35mm f/2.8] at [http://www5b.biglobe.ne.jp/~nikonsp/ 石の上にも３０年](''Ishi no ue ni mo 30-nen''; '30 years on the stones'; the site features pictures taken while walking along Japan's railway tracks)<!-- don't try this at home, kids -->
* [http://hcwc.way-nifty.com/blog/2009/01/post-f3b1.html Picture taken with a Prominar 100mm f/2 on an Epson R-D1s] at [http://hcwc.way-nifty.com/blog/ Camera Hiking]


{{M39}}

[[Category: Japanese lenses]]
[[Category: 39mm screw mount]]
[[Category: 42mm screw mount]]
[[Category: Kowa]]