Kogaku K.K.) RF W-Nikkor.C 1:4 f=2.5cm (25mm f/4.0)
ultra-wideangle lens for Nikon S-Mount Rangefinder cameras
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Section 10.04.2008 3rd.
A brief background on the German
version:- Topogon design
has a double Gauss optical arrangement. It was first introduced by Dr. Robert Richter
back in 1933 by modifying the Hypergon (1900, Goerz) by adding a pair of concave
elements to the Hypergon design (comprised of two convex meniscus elements that have
the same radius of curvature.) without disturbing the symmetrical configuration of
the lens system and delivering the objective of correcting longitudinal chromatic
aberration and spherical aberration. Due to the optical nature with a high resolving
power and optical characteristic in excellent flatness of field, low distortion and
curvature of field, all these which added to its wide angle coverage; thus, Topogon
design was often pursued by army in its development during the World War II for surveillance
aerial photography and other special application to spy on enemy locations/formation.
During post war period, East German Carl Zeiss Jena saw the potential of the design
and began commercialized the 2.5cm lens for 35mm photography back in 1950. Nippon
Kogaku, on the other hand, was also believed to have been exploring practical usage
of the Topogon lens type for the Imperial Army where its research effort was put
to commercial application after the war. The Zeiss version was marked T* coated but
the production for this lens by Zeiss Jena was only lasted for a few years. Based
on some references, less than 700 units of the Zeiss 2.5cm Topogon were being produced
by Zeiss Jena between 1950~1953.
to image profile of Carl Zeiss JENA TOPOGON 25mm f/4.0
Zeiss version of the 2.5cm ultrawide had NOT been designed with any dedicated accessory
finder along as standard accessory. But rather, owners of the Zeiss Topogon lens
had to use the Zeiss Turret Finder. Neither any of the available contarex camera
has built-in bright-line frame for such an extensive wideangle coverage, so the use
of the Turret is essential for practical shooting sequence. It was learnt that Nippon
Kogaku K.K. was already began selling a version of the 2.5cm f/4.0 lens in a similar
Topogon design to other camera labels during or post war era.
Shown are the Carl Zeiss Jena Turret 440 Finder and Zeiss Ikon's 440 Turret. The Zeiss Jena Turret has a 2.8cm marking
while the latter has provision for an even wider range at 25mm, 35, 50, 85 and 135mm
settings / focal lengths.
Credit:- Image courtesy of Mr. Mike
Otto® <email@example.com> URL: Pacific Rim Camera, who also operates a popular Ebay Store. Image Copyright © 2003. All rights
reserved. Pacific Rim camera can also be reached by mail to: Pacific Rim Camera 1965
Davcor St SE Salem, OR 97302 (503) 370-7461 Fax number is (503) 370-8801. Please respect the
visual property of the contributing photographer.
A visual comparison
between a Nippon Kogaku K.K. early Screw Mount 2.5cm f/4.0 and Carl Zeiss Jena's
2.5cm Topogon ultrawide.
Credit: Image of the Carl
Zeiss Jena Topogon at the far left courtesy of Photo
Germany. The Company also maintains an active EBAY
trading many used and new photo equipment of various labels. Photo Arsenal can be
contacted via ebayshop @ arsenal-photo.com. Image(s) copyright © 2008.
All rights reserved. Please respect the visual property of the contributing photographer.
|Basic information on Nikon (Nippon Kogaku K.K.) W-Nikkor.C 1:4
f=2.5cm M39 Screw-Mount (SM*) ultra-wideangle
Year Introduced: June of 1955 (Nikon stated date. Other sources it was available
there is actually two versions of the Nippon Kogaku K.K. (Nikon) W.Nikkor 1:4 f=2.5cm
ultra-wideangle lens. The older version which bear a Leica M39 Screw-mount (SM) and
many people thought Nikon had this Nikkor wide made for many other camera labels
such as Leica, Nicca, Tower and even on the Canon RF models earlier than offficial
released date. The old SM version has a much lighter weight and a more compact dimension
than the Nikon Bayonet mount version introduced later. The old lens was believed
to have been supplied in all chrome finish. The most noticeable visual between the
two is, the SM version comes with the distance scales engraved in black on the large
metal ring (closest to the camera body).
images courtesy of Mr. Kenneth Frey from his Ebay Store Image Copyright © 2008. All rights
reserved. Please respect
the visual property of the contributing photographer.
scales are actually printed at the front as well as at rear section of the ring.
Depth of field scales can be read at the metal lens barrel at the middle lens barrel.
All the scales are marked in feet and no meters scales were provided in this version.
Unlike the Zeiss Jena counterpart, Nikon own was supplied with a dedicated accessory
optical finder that has a rounded metal front section with a rectangular lens diaphragm
outline. The rear/center portion of the finder has a black finish. There is another
circular metal frame rounding the eyepiece at he back with "Nippon Kogaku, Japan"
printed circularly around the eyepiece. A "2.5" is printed at the top of
the finder. All the known version of the finder for 2.5cm which surfaced in the used
equipment market so far have not seen to be serialized. The photo shown at the left
hand side shows a few of the various accessories. which include original Nippon Kogaku
KK lens cap, Finder, adapter/lens shade for Series 6 filters as well as the leather
" .... I've had a lot of fun with it, but my interests are changing so time
to let it go. I used it mostly with a Canon VI-L, Canon 7, and a Minolta 35 that
I painted black that this lens looked really cool on - not to mention that it produced
some great images for me. Only 950 of these were made in Leica screwmount compared
to almost 2000 in Nikon mount, so these are a bit tough to find these days. I have
owned the Nikon mt. version and I must say I prefer the screwmount version to actually
use for a couple reasons. Number one the lens hood screws on instead of the flimsy
feeling bayonet hood on the Nikon that always felt like it was about to fall off.
Also the apertures are easier to change on this lens, the outer ring rotates instead
of having to reach inside the lens and slide that hard to get ahold of little tab
on the Nikon. Finally there is an actual focusing knob on this one compared to the
wheel focus only Nikon version. Like the Nikon version this one is amazingly small
and compact, a real joy to use. The glass is clean and clear, no scratches, haze,
or fungus. Looking super close there may be a couple tiny, tiny internal dust specks,
but they are almost impossible to even see - the lens really in beautiful optical
condition. The aperture blades works nice and smooth over the full range. Focus action
is also very smooth, not too loose, not too tight. Only very light external wear.
Comes with correct two piece lens shade and filter holder, I think it takes series
6 filters, it is either series 6 or 7, I think it is 6 but I forget, if you really
want to know email me and I will go dig out a filter to see which one it is. Also
comes with the 2.5cm finder marked L on the bottom for Leica. the finder is in very
nice shape, with clean and clear optics. Also included is a Nikon front cap, sorry
I do not have the rear cap for the lens. Also a Nikon round leather case is included.
Another nice thing about this lens is that it is rangefinder coupled, unlike the
Voigtlander 25mm which is not. The lens is a four element design, almost symmetrical,
with extreme curvature to the outer elements, really must have been a tough lens
to manufacture back in the fifties. Just a beautiful and rare lens, a lot of fun,
especially since there are so many cameras that you can use this lens on. ...."
- Kenneth Frey -
|The SM version
of the 2.5 RF Nikkor lens has a minimum focusing distance at approx. 1m (3.3ft).
A non-colored Infrared compensation index is provided next to the focusing index.
And when rotating the aperture, the index that located at the front section around
the slight recessed circle near the lens element will also change accordingly. The
aperture ranges of this SM version 2.5cm Nikkor lens ranges from f/4.0 to a minimum
f/22 with a 6-f-stops setting for wider depth of field control option. In comparison,
the Zeiss Jena 25mm f/4.0 Topogon has a more moderate, less appealing f/16 minimum
aperture. It was not known when
the SM version was discontinued. But after Nikon had introduced their own rangefinder
Nikon in 1948, their emphasis was refocused to develop their own bayonet version.
* If you still find the few versions mentioned here
a little confusing. Wikipedia explained some relations: " .. The Leica screw-mount ("SM"
also known as M39) cameras developed for lens manufacturer Leitz Wetzlar by Oscar
Barnack; Contax cameras manufactured for Carl Zeiss Optics by camera subsidiary Zeiss-Ikon
and, after Germany's defeat in World War II, produced again and then developed as
the Ukrainian Kiev), Nikon S-series cameras from 1951-1962 (with design inspired
by the Contax and function by the Leica), and Leica M-series cameras..".. Here
shown the different versions which includes a Leica thread SM version.
Credit: All images courtesy of Mr. Kenneth Frey from his Ebay Store
Image Copyright © 2008. All rights reserved.
|Next:- Co-Moderator for the MIR's Lens Message Board, Robert G. Middleton also had explained "..
The M39 designation is used for a screw mount for camera lenses. It is what some
people call the old screw thread Leica mount, used on the rangefinder models prior
to the release of the M mount models. Technically the 39mm diameter thread used on
the pre M series Leicas, should not be designated M39 - This designation is for a
thread with BOTH a metric diameter and METRIC pitch. The 39mm thread, as used by
Leitz had an Imperial or INCH pitch - this anomaly arose because the RMS thread specifications
were the norm at that time for optical instruments. RMS was an imperial or inch standard.
All Leica copies use the true M39 designation thread - except perhaps some very early
FEDS, which were a direct copy of the Leica 1. In practise however, the difference
in thread pitch does not stop Leica lenses fitting on the copies and Russian lenses
fitting on the Leicas. Only in rare cases, when machining tolerances come into play,
will you find trouble in mating a Leica Screw Mount item with a M39 mount item. ..."
- Robert Glenn Middleton <(firstname.lastname@example.org) -
|Credit:- Image courtesy of Mr. Darrryl Schaeffer from DS camera @ EBAY <contact:- dscamera @ aol.com>. Image Copyright © 2008.
All rights reserved. Please
respect the visual property of the contributing photographer.
|Credit: Image courtesy of Mr. Peter Coeln from LEICA Shop®, Austria who also operates a popular Westlicht Auction House. Image Copyright © 2008. All rights
reserved. Please respect the visual property of the contributing photographer.
|Nikon (Nippon Kogaku K.K.) W-Nikkor.C 1:4 f=2.5cm (25mm f/4.0) S-Mount (Bayonet) ultra-wideangle lens
Introduced: March, 1955#; Discontinued: August, 1969
RF W.Nikkor 1:4 f=2.5cm ultrawide which designed specifically in Nikon own bayonet
mount was first being marketed in November, 1953. After its official debut, it was
once regarded as the widest lens available for Nikon RF system until the release
of another Nikkor-O
1:4 f=2.1cm (21mm F/4.0)
in 1959 which gave a span of difference in 6 years for another new ultra-wideangle
dimension for RF Photography. The 2.5cm Nikkor lens was actually being introduced
barely a year after the 1952's W-Nikkor 1:3.5 f=2.8cm wideangle. Which means to say,
the 25mm RF Nikkor has remained as the only choice wider than 28mm during that era.
Unlike the earlier featured Leica SM version, the bayonet mount version has quite
a different physical appearance, as well as operational sequence for shooting. Due
to the unique lens design of a symmetrical optical formula, which attributes to its
exceptional flatness of field and minimal vigetting, it has indirectly contributes
to its extremely compact design. In fact, when the lens is mounted onto a Nikon RF
body, and when you view it side way, the physical extension of the lens is just only
a few centimeters protruding outwards from the lens mount/camera body. # Nikon stated date in their official web
site. Other sources: Both Nikon Hand Book / Nikon RF illustrated History suggested
Credit: Image at the left
courtesy of Mr. Kelvin LI from his popular gokelvincameras@Ebay Store which retails for many hard-to-find Nikon,
canon, Contax oldies. The front view of the Nikkor-W 2.5cm f/4.0 above courtesy of
"Ebay - Mathew Duren" URL: Adorama.com, who also operates a popular Ebay Store. Image Copyright © 2003. All rights reserved.
|You don't find
a conventional aperture ring on the lens, instead you have to manually hand set the
f-stop via a slide/dial (see below) inside the slightly recessed front section of
the lens. On the other hand, focusing is via a sharp edged wheel/dial. It was not
entirely a good design in this respect as when the lens is mounted, there is little
space for control. Equally you don't find a traditional located focusing ring on
the lens barrel for easy visual when shooting or determining the focusing range.
I guess Nikon optical engineers probably had put up a lot of thought to accommodate
the adoption of its simple optical design and fitted with a mechanical outfit which
has resulted in such a compact ultrawideangle lens to be realized.
a practical stand point, I might not agree the lens is a very friendly tool for shooting.
For an example, you may have to tilt your camera upward just to change/check aperture
and focusing distance. Although the tiny front exposed lens element is deeply recessed
at the front, but still - photographer has to be extremely cautious during making
shooting adjustments. As none of the prevailing Nikon RF models have a built-in bright-line
frame for its extensive picture coverage, so, focusing is via manually by estimation
of distance with depth of field control. The DOF scales are not printed on the top
so, you also have to tilt the camera upwards to check all the settings. Thus, this
can be considered as rather awkward to use if responsive shooting action is required.
<<<--- Shown here is an
older, original chrome ring version. Difficult to locate such a lens now but I have
found a picture via the Nikon RF magazine. For other views refer to the suggestive
|Based on records
and various sources, there are actually TWO bayonet-mount versions available throughout
its entire production cycle. The early model (1953) has a solid and rigid all chrome
on brass construction (refer to the 2nd picture (B)
below); it was revised after 1956 onwards with a black version (the one shown a few
main paragraphs used or simply refer to the third photo (C)
below). The black version is significantly lighter, weighing only 2.5oz as compared
to the chrome/brass model which weighs almost 1X heavier at 4.5oz (approx. 128g).NOTE: The Black Version:
Released in July, 1956, lens barrel was changed from chrome-plated brass to black
light alloy in line with other lenses to standardize the outlook design.
I have been
trying to locate some pictures to let you take a look how the Leica SM mount 2.5cm
Nikkor-W (A) and Nikon's own S-mount when mounted onto
a RF Nikon body. The Japan Nikon Kenkyukai Tokyo had a Christmas
gathering back in 2004 where members had presented such a combination. Take a VISIT for the original
pictures along with many other rare RF Nikon bodies/lenses.
I am not trying to pick on a lens designed 50 years ago but there are just simply
too many confusing numeric printed within the tiny circular area that surrounding
the lens element which comprised of three circles of printed numbers/data, aperture
settings from f/4.0 ~ f/16; with the depth of field scales opposite (along with a
red (R) infra
compensation index. The outer circle is printed with various distance scales. The
outer ring is encircled with "Nippon Kogaku, Japan" with Serial Number
and the lens data "W-Nikkor.C 1:4 f=2.5cm" at the opposite. Come to think
of it, size of lens data/S/N/Company name are far more prominent than the practical,
frequently used figures/numbers engraved/printed for photography - well, like it
or don't, I don't call all these a very friendly arrangement.
<<<--- just take a look at the
few photos displayed here with the confusing state and you will agree with me that
these areas were not well handled.
Supplementary Info:- The re-engineering
task of the S-mount version of the W.Nikkor 2.5cm f/4.0 was believed to be headed
by a Nikon optical designer, Mr. Hideo
Azuma. | Here is an interesting article | prepared
by Mr. SATO, Haruo which was originally written for Nikon Club.
It has addressed many technical aspect in designing and implementation of the 2.5cm
Nikkor during actual production. As explained in Sato's article, despite it was a
commissioned assignment by his Company to replicate the German designing concept
for a workable solution for a Nikkor-W; one significant achievement by Mr. Hideo
Azuma was his achievement in overcoming a shortcoming found in the Zeiss version
esp. around the vignetting factor. In comparison, Mr. H. Azuma had improved the Nikkor
lens brightness around the edge of the image field, ensuring evenness on the outer
* Incidentally, Hideo Azuma was the mentor to more
famous another Nikon lens designer, WAKIMOTO, Zenji who had developed the famous
ultra-wideangle lens, the early Micro-Nikkor as well as the special IC-inspection Ultra-Micro-Nikkor lens group.
|With a wide angle
of view (80.5° (50° x 70° well, the lens may mean nothing if it is measured
by modern standard, but
you have to understand,
was really "something" half a century ago..citing the fact that the first ultrawide in
reflex version with a different
retrofocus design for MF Nikkor 24mm (meaning - NO Mirror-Lock-Up is required when
used with any reflex Nikon SLRs and permits direct viewing and metering) was only
being developed in 1967). This RF Nikkor wideangle lens offers an unusually wide
perspective of 25mm for the Nikon rangefinder bodies. It delivers excellent flatness
of field due to use of the unique symmetrical design as well as containing vignetting
to a minimal level. Some references said the W-Nikkor had used rare earth glass in
its optical composition which enables common aberrations to be controlled to enable
realization of such an extreme picture angle yet be able in such a remarkable compact
lens package. I am not sure if the series were all being coated but most of the versions
that had surfaced over the last few years are carried with a W-Nikkor.C inscription after the lens
data (Well, to be honest, for the last few years - I had been very patience to wait
and gather pictures/photos at Ebay (esp. by various frequent contributors to MIR
site), which in anticipation one day, I will create a site on RF Nikkor here).
Use of separate optical finder requires
focusing via conventional depth of field /distance estimating method (This lens is
similar to the 2.1cm - where accurate focusing is not essential as long as it is
within range, other than its closest focusing distance where one has to take note,
but clever use of depth of field manipulation should yield adequate range of sharp
focus zone. Further, by combining mid aperture in this ultrawide, it enables quick
pre-focus shooting. Well, as none of the original old series of RF Nikon models provide
TTL metering and thus, user may has to make use incident light meter or use experience
to counter for metering. Well, Nikon did produced an own labeled exposure meter.
However not all RF Nikon can make use of it as It was only being introduced after
the Nikon SP (1957) because SP was the first RF Nikon that offers a non rotating shutter
speed dial which enables the exposure meter be coupled onto camera. NOTE: Canon has this similar change of the non rotaing shuter speed dial
a year later than the Nikon with the Canon VI-L model in 1958.
images (lens hood, Optical Finder and rear/side views above) herein courtesy of
Mr. Kelvin from his popular gokelvincameras@Ebay Store which retails for many hard-to-find Nikon,
canon, Contax oldies. All images Copyright © 2008. All rights reserved.
Along with the
2.1cm (21mm) ultrawide and 25cm (250mm) telephoto lenses; this 2.5cm Nikkor-W has
remained as the only ODD fixed focal length Nikkor lens that you can find
within the decades of produce in their ever growing Nikkor lens group. Well, after
the Reflex Nikon F was
officially announced in 1959, Nikon first offered reflex Nikon photographers with
a non Ai version of the MF Nikkor 24mm in 1967. Over the years, the popular manual focus 24mm
lens group had gone through
many phases of lens updating program which was directly inline with the corresponding
development of metering system in the Nikon SLR camera system. The autofocus version of the 24mm (Ai-S/1985 and AF-D/1993) was among the original series of autofocus lenses being introduced with the first*
integrated autofocus Nikon camera body (Nikon F501 / N2020). The W.Nikkor
1:4 f=2.5cm ultra-wideangle lens which had served many Nikon RF users throughout
the years, captured history, recording major events/happenings in the world via their
Nikon, has remained itself as
a highly collectible optical imaging tools to all Nikon enthusiasts worldwide today.
|* NOTE:- The first Autofocus Nikon that went on
commercial production was the Nikon F3AF (1983)
but most people referred it as a "prototype" which being produced to test
the market. It has no full system accessories built around the camera. Unlike the
F501/N2020 which began with a new evolution in the AF-Nikkor lens family for all
Nikon AF bodies that followed, only two dedicated F3AF Nikkor lenses were being offered thus far; thus we still referred the Nikon F501/N2020 as
the first Nikon AF SLR model.
It is also interesting to note that Canon also had followed Nikon's path by introducing
a version of the Canon Rangefinder version of a (RF) 25mm
lens a few years later in 1956. The Canon RF wideangle lens was also adopting the
Toppogon lens type. However, Canon's version has improved it with a faster maximum
lens speed than the contemporary Zeiss / Nippon Kogaku design by coming out late.
Besides, it has separate aperture, focusing rings just like a normal lens. (see illustrations
at the left).
Specification for W-Nikkor-C 1:4 f=2.5cm wideangle
Nikon S-mount for Nikon RF models or early M39 Screw Mount
Focal Length: 25mm (2.5cm)
Picture Angle: 80.5° (50° x 70° ); Lens Coating: Single Layer
Maximum / Minimum Aperture: f/4.0 ~ f/22; Diaphragm: Manual
Optical Construction: 4 elements in 4 groups ("Topogon" Type)
Minimum Focusing Distance: 91cm (3 ft) ~OO
Filter Attachment Size: Series VII (43mm); Hood: 47.9mm screw-in type
Dimension:- 55.8 mm dia. x 31.8 mm long (overall)
Weight (body only): approx. 126g (4.25oz) for Chrome version; 2.5oz (Black);
Screw Mount (Leica Thread):- approx. 3-3/16 oz (75g)
Optical Finder (2.5cm model); special rear lens cap. Optional: Screw-in
type lens cap / Lens hood 34.5mm, optical filters Series VII for S-Mount; Series
VI for Leica SM etc. F-S/S-F mount adapters: no info.
Two major versions in either Leica thread M39 Screw mount or S-Mount for
Nikon RF models (Chrome 1954 and Black (1956) version). Bayonet System to mount lens
cap and the Series VII lens hood. Serial Numbering used:- Chrome/Brass S-Mount
starts from 402500 ~ 403500. Lighter weight black ring version up to 405000. Total:-
Approx. 2,500 Units. Ref: Robert Rotoloni's An
Illustrated History on Nikon Rangefinder camera.
|Credit: Image(s) courtesy of Mr David Schorer® who also operates a popular Rhona45th@EBAY
STORE. Image Copyright
© 2008. All rights reserved. Please respect the visual property of the contributing
W-Nikkor-O 1:4 f=2.1cm | W-Nikkor.C 1:4 f=2.5cm
| W-Nikkor.C 1:3.5
f= 2.8cm | W-Nikkor.C 3.5cm lens Group (3.5/2.5/1.8) | Stereo-Nikkor 1:3.5 f=3.5cm | 5cm (50mm) lens group | RF Micro-Nikkor 1:3.5 f=5cm | Nikkor-P.C 1:2 f=8.5cm lens group / Nikkor-S.C 1:1.5 f=8.5cm lens group | Nikkor-P.C 1:2.5 f=10.5cm
lens group / Nikkor-T 1:4 f=10.5cm | Nikkor-Q.C 13.5cm lens group: 135/4, 135/3.5 Early
/ Last Version, 135/4 Bellow lens
| Nikkor-H 1:2.5
f=18cm | Nikkor-Q 1:4 f=25cm
| Nikkor-T 1:4.5 f=35cm | Nikkor-T.C 1:5 f=50cm | Reflex-Nikkor 100cm f/6.3
for Nikon Rangefinder cameras
Optical Finders (4 parts):- Fixed Focal length Finders (index page): 2.1cm,
3.5cm, 35cm Stereo,
5cm, 8.5cm, 10.5cm,
13.5cm | Variframe / Varifocal / Sport-frames
| Nikon Reflex Housing
S36/S72/S250 Motor Drives
/ S36 Manual |
light meters | Nikon RF Flash/Speedlights | Close-up
photography / Repro Copy Outfit / Nikon Bellow Focusing Device (in progress) | Cases/Compartments | Lens & body caps,
Original Price Lists |
Related info:- Main index page
for Leica/Leitz | Contax/Carl Zeiss | Seiki Kogaku (Canon)
| Message Board | lenses | Message Board | RF cameras
Nikon RF-Nikkor lenses
(Rangefinder):- Main Index Page
Nikkor lenses:- Main Index Page
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and content which made up the basis of the site. Note:certain
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and/or contribution from surfers who claimed originality of their work for educational
purposes. The creator of the site will not be responsible for may discrepancies arise
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"Nippon Kokagu KK" & "Nikkor" are registered trade name of Nikon Corporation Inc.,
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