martes, 9 de febrero de 2010

LEICA M7 WITH W·NIKKOR-C 2.5 CM F/4: AN EXOTIC AND WORKING COUPLE

Text and Photos: José Manuel Serrano Esparza


The Leica M7 is probably the 35 mm analog rangefinder camera featuring more functions ever made by the German firm, with a core made up by a very accurate rangefinder, three choices of viewfinder magnification (0.58x for wideangle lenses and eyeglass wearers, 0.72x as universal standard magnification, and the 0.85 version for lenses with medium and long focal lenses up to 135 mm, with brightline frames designed accordingly for each magnification and being manually or automatically activated in the viewfinder), and an electronically controlled, vibration free and horizontally running state-of-the-art focal plane cloth shutter working extremely smoothly and practically without vibrations, it all being fostered by a very reliable TTL semispot metering, which is slightly more accurate than the very precise one featured by the Leica M6 and Leica M6 TTL.

All speeds are electronically governed, except 1/60 sec and 1/125 sec that are mechanical, in such a way that we have got security margin to spare, because if suddenly the batteries drain, we can use either of these speeds to take the picture.

Aside from the traditional manual selection of shutter speed and aperture by means of the light balance in the viewfinder, which has been thoroughly proved for a lot of decades in preceding models of Leica M cameras, the M7 also sports the automatic shutter speed priority option, which enhances even more the great quickness of usage based on a highly precise large base RF enabling very consistent focus once and again, even with low contrast objects and even under very dim light conditions, helped by the top-notch high luminosity of the slew of Leica M lenses, excelling in terms of optical and mechanical quality and rendering exceedingly high resolving
power and contrast even at the greatest apertures for which their design was usually optimized, bringing about crystal clear images, loads of detail and great color.

A quality without compromise, far from any programmed obsolescence and a true photographic tool to last a lifetime, lacking lots of buttons or knobs, and in which the photographer has got the control at every moment and takes the decisions on the keynote of paying attention to the essential and really important things, for tackling the photographic act with the least ammount of clutter, in an unobstrusive and inconspicuous way, very often with the further chance of using hyperfocal techniques holding sway over the desired depth of field area, which often beats in accuracy and quickness the best AF of professional SLR cameras in some genres as the candid
shots or streeter to practical effects.


But even if we shoot with Leica M high luminosity lenses at apertures between f/1 and f/2.8, the M7 with its manual focusing through RF will beat the best current pro reflex analog and digital slr cameras in terms of accuracy, because der Entfernungsmesser performance is based on visual acuity, while the manual focusings of the best 35 mm professional manual focusing analog reflex cameras lie on groundglasses based on contrast and the best current top of the line
professional analog and digital SLR cameras like the Nikon D3 with superb, very accurate and extremely fast phase detect AF using an array of prisms, lenses and a secondary sensor to determine not only whether the image is in focus or not, but also by how much it is out of focus and in which direction, after which the camera can adjust in only one step the focus setting to exactly the position needed, so phase detect AF systems are most times much faster than contrast detect ones.

In spite of it, and however amazing it may seem, the effective measurement base of the Leica M7 rangefinder (40.2 mm the 0.58 model, 49.9 mm the 0.72 model and 58.9 mm the 0.85 model) enables this camera to get more accuracy of focus, because its optical system is based on visual acuity and it is more precise than a contrast based one, and even better than the most updated fast phase detect AFs, something which is enhanced by the new M7 finder windows which are covered with scratch resistant multi layer coatings to foster contrast and brightness. Only the Zeiss Ikon rangefinder camera boasting a 0.74x viewfinder magnification viewfinder and a very big effective 55.9 mm RF base can match the M7 focusing accuracy.

We mustn´t forget that though being limited to lenses with focal lengths between approximately 18 mm and 135 mm and obviously not the best choice for macrophotography, microphotography and genres needing long and very long teleobjectives like sports and wild life photography, the Leica M7 goes on the tradition of the legendary Leica M System which has very solidly proved its virtually unbeatable high precision for 56 years in the photographic contexts for which this
kind of RF cameras were created, excelling in top-notch quality of the materials used (most times noble metals like brass and aluminum).

And unlike SLR systems in which distance measurement through the lens is determined by focal length and lens speed, the measurement base in the rangefinder of the Leica M7 remains always the same regardless of the lens being used, getting huge levels of reliability with the split and coincident image rangefinder, a masterpiece of optical and mechanical craftsmanship made up by more tha 150 parts. That´s why its accuracy is superior to that of SLR cameras, specially with wideangles and standard 50 mm lenses, a trait which in the M7 is stalwartly backed up by the viewfinder window that boasts a top-notch antireflection coating that minimizes the flare of the rangefinder patch happening in some contexts when strong light sources shine slanting into the
finder.



If we also bear in mind that the time lag of the shutter between pressure of it and firing is of 12 milliseconds (much shorter than the shutters sported by top-of-the-line SLR AF analog and digital professional current 35 mm cameras), we get the hang of the whole thing: to take pictures with the Leica M7 is something more spontaneous, relaxed and convenient, using a very compact and light camera body, along with very small lenses most times second to none in
optomechanical quality in the 24 x 36 mm domain, generating a very low level of noise when shooting, comparable to a whisper(the Leica M7 beats in this regard both the M3 and M6 when using slow shutters speeds while when taking pictures at medium and high speeds the
almost imperceptible levels of noise are on a par), the latter being feasible because instead of the levers, cams and gears driving the speed adjustment in classical Leica M cameras like the M3 and M6, an electromagnet for each curtain is now responsible for the timing of the release, and the absence of the gear train present in classical Leica M models bringing about a very slight noise during the delay of the second curtain when using slow speeds turns into silence with the M7.

Besides, a new rollerbearing strengthens the main roller of the M7 shutter, and it makes a difference regarding its precision and seamless duration under stress through many decades, with a remarkable speed steadiness of the traversing slit.

As to any doubt on the capacity of the Leica M7 to work in harsh climatic conditions because of its dependance on batteries and inner electronics, it has been proved that the shutter operates flawlessly and boasts higher accuracy than the mechanically governed in M3, M6, etc.

Regarding flash synchronization, the Leica M7 has the possibility of being used with appropriate flash units set for the first or the second curtain, with the added benefit of a high speed sync choice.

On the other hand, it is the first Leica M analog model to include automatic film speed setting with standard DX coded 35 mm film cartridges.

It is a camera built with a smart mixture of old and new product technology, oozing a very painstaking care devoted to the design of the viewfinder, shutter and the die-cast housing, with a tremendously exacting material selection and treatment, engineering quality and an almost entirely manual assembly following thorough artisan guiding principles.


Needless to say that the M7 is a milestone in the Leica M concept development, harbingering in some conceptual aspects the subsequent development of the extraordinary digital rangefinders Leica M8, M8.2 and M9, always understanding that it all greatly stems from the solid foundations laid by Oskar Barnack from 1913 and endorsed by Ernst Leitz II in 1924, who made the historic decision that the little 24x36 mm film camera concept designed by Barnack and featuring screw mount would go into production (being introduced at the Leipzig Spring Fair of that year), and was followed from fifties by his sons Ernst Leitz III, Ludwig Leitz II and Gunther
Leitz, who encouraged the development of the Leica M System, masterminded by its two driving forces: Willi Stein (Head of the Photographic Design Department) and Hugo Wehrenfenning, respectively creators of the Leica M camera and the M bayonet concepts, which would give birth to the first Leica M3 in 1954, without forgetting the very significant role performed by Otto Siegmund and Werner Keiner, who had coordinated during the previous years every design solution regarding the Leica rangefinder cameras, and the invaluable help of Friedrich Gath, an outstanding expert in shutters technology, whose contribution was instrumental as a collaborator of Willi Stein, improving the calibration intervals uniformity of the shutter speed times (not very consistent until then) by means of the designing of a new focal plane shutter
created from scratch to that aim (whose patents date back to 1934 and 1935) which
were progressively improved and tailored for the new Leica M3 as a workable solution in the beginning of fifties, with the added benefit of a new delay mechanism conceived to be rotated, a further brainstorm by Hugo Wehrenfenning through which it was possible to eliminate two problems inherent to screwmount cameras: the friction during the shutter travelling and the somewhat erratic delay mechanism when using slow shutter speeds frequently bringing about the shutter being open in the meantime.

The possibility opened by the M7 of choosing automatic shutter speed priority allows the photographer to attain a more spontaneous and relaxed photographic activity, because he is not bound to be aware about setting the correct exposure or to adjust it, in frequent contexts in which light conditions are changing, so he can pay his/her utter attention to framing, composition and focusing, immediately after having selected the subject, since when the shutter priority AE is on, the camera constantly measures the light.

It´s clear that a Leica M experienced photographer will be able to make things without problems with a Leica M3, M2, etc, operating quickly without any built-in TTL metering and getting a very high rate of accurate focusing and much better pictures than a bad photographer with a Leica M7, and that the aperture chosen will go on being a very important aspect to control depth of field, selective focusing and picture quality, but with the M7 the option of relying on a well proven electronic system which makes the task of selecting the appropriate speed in a very fast way, undoubtedly liberates the photographer of the work and time necessary to manually
set the shutter speed with previous Leica M cameras, while you go on preserving the control of the significant items and taking the decisions with a minimum intervention of electronics. It is also evident that frequently a picture of a brief moment is missed because to manually set the correct exposure means to take some time and then that instant may have elapsed, so the advantages of the M7 in this respect, with its available shutter speed priority AE are very significant when the photographer has to tackle environments where he must react fast under changing luminic levels, so the original philosophy of the rangefinder Leica camera as an
optimized photographic tool for handheld shots, even at very slow speeds under dim light conditions with iso 100 and 400 films without trepidation, taking advantage of both the lack of the tilting mirror present in both analog and digital slr cameras and the excellent mechanical and optical quality of rf lenses designed without any compromises.

On the other hand, the sturdiness of the Leica M7 and its ability to endure a lot of years of hard professional use is impressive, because only high quality materials are used in its manufacture. One example will suffice: its top cap and base plate are made with solid brass, while the camera body consists of very special simultaneously light and highly tough diecast aluminum.


The W-Nikkor.C 2.5 cm f/4, designed by Hideo Azuma in 1953, is a minute jewel in itself, with very small dimensions and weight (even smaller and lighter than the tiny 61 g Russian Orion-15 28 mm f/6 in LTM mount) rendering it a relish to use.

Obviously, it is far from the optical performance of much more modern optical designs of similar focal length and maximum aperture around f/4 featuring multicoatings like the not coupled Cosina Voigtlander 25 mm f/4 SC Skopar for Nikon and Contax rangefinder cameras (and also for screwmount Leica rangefinders and Leica M cameras through adapter), the coupled Cosina Voigtlander 25 mm f/4 SC Skopar in Leica M mount, and differences would be much bigger in all
conceivable parameters if comparison is made with the superb Elmar-M 24 mm f/3.8 ASPH or with the trio of high luminosity 24/25 mm wideangles made up by the Elmarit-M 24 mm f/2.8 ASPH, the Zeiss Biogon T* 25 mm f/2.8 ZM and the Summilux-M 24 mm f/1.4 ASPH, all of which clearly outperform the W-Nikkor.C 2.5 cm f/4, a lens made approximately half a century before.

But it doesn´t matter at all, because this charming wideangle Japanese vintage lens is much smaller and lighter than all aforementioned top class wideangles in the 24/25 mm realm, and it is still able to get good pictures, so the photographer using it can attain unsurpassed levels of compactness and convenience of handling and transport, as is the case coupled to the Leica M7.

If besides we realize that the lens only protrudes 0.95 cm from the camera and that it is possible to shoot handheld at very slow shutter speeds of up to 1/4 sec without trepidation using first class modern 35 mm black and white films like Fuji Acros 100, Kodak T-Max 100, Kodak T-Max 400 New, Argenti Nanotomic-X shot at iso 100 and 200 and developed with Nanodol, etc, and current iso 100 color films like Kodak Ektar 100, Fuji Reala, etc, with the chance of greatly improve the quality of image possible during fifties (in which chemical emulsions were much
grainier) preserving that very special aesthetic of image inherent to classic Nippon Kogaku rangefinder lenses from the starting halcyon days of Nikon, we begin experiencing unique sensations.



This was a Japanese great optical tour de force design, because 57 years ago it was strenuously hard and difficult to make such a small extreme wideangle lens featuring such a little diameter, and the manufacture of its four elements became an exceedingly hard and painstaking toil, specially the two very thin and brittle concave elements of its optical formula, whose treatment was very cumbersome.

On the other hand, each W-Nikkor.C 2.5 cm f/4 produced needed a very special cleaning equipment during the manufacturing stage.

Hideo Azuma studied very thoroughly the four elements in four groups German Carl Zeiss Jena Topogon 25 mm f/4 for Contax rangefinders, designed three years before, in 1950, on which the 1953 W-Nikkor.C 2.5 cm f/4 wideangle lens is based and from which it inherits the deep aperture ring set from inside the lens.

This Topogon type of wideangle has got very solid foundations and its roots date back to the Goerz Hypergon designed by Emile von Hoegh in 1900, an impressive large format super wideangle for that time and for the current time, already within XXI Century, with a maximum relative working aperture of f/22 and still delivering a very good image quality according to current standards, featuring the same radius of curvature in the two convex meniscus elements included in its symmetrical optical formula and above all and what´s more important, attaining an angle of field of 135º with 0 geometric distortion thanks to its completely symmetrical
design and its fairly simple construction with only two very thin and deeply curved meniscus elements that almost form a sphere and are located around a central stop.

The Hypergon had a huge light fall-off at the edge of the plate that exceeds the cosine law regarding the way in which irradiance varies with slope angle, and in order to compensate it, had a built-in star aperture on the center, which the photographer had to spin during the exposure, working like a sort of graduated neutral density filter and levelling the exposure with respect the negative corners.

It´s true that some more complex and much more modern large format wideangles featuring a higher number of elements and groups in their optical formula beat the Hypergon in terms of resolving power, but there isn´t any modern large format wideangle lens able to cover 135º and if we add the key aspects of its absolutely lack of distortion (depicting each and every line of buildings, objects, different means of transports, all kind of structures, etc, perfectly straight and accurate) and its incredible compactness bearing in mind that it has the widest angle of coverage
of any LF wideangle lens ever made and that the very big negative of 8 x 10 (20 x 25 cm) and bigger is much more tolerant in sharpness and focus than 35 mm film, we do understand why Hypergons were and are so legendary from their very inception approximately 110 years ago, we do understand why this lens has been and is so admired and coveted, and above all why it has exerted for more than a century such a big influence in the development of super wideangle lenses in which top priority - even if maximum aperture had to be moderate- was complete lack of distortion, a flat field across a very wide angle of coverage, low astigmatism and coma and remarkable compactness.

The Hypergon is not corrected for chromatic aberration, also featuring a big amount of oblique spherical aberration at maximum f/22 aperture (some decades would have to elapse until the appearance of Roosinov/Biogon wideangle designs much more optimized for works at the largest apertures), though this drawback is reduced by the use of a smaller f stop opening once the image is focused, usually around f/32, from which sharpness is very good, also being true that the element spacing is tremendously small, so Hypergons were never delivered in shutters.

Hideo Azuma had in mind all these aspects related to Hypergons, along with four other optical designs:

a) The 4 elements large format Zeiss Topogon designed by Robert Richter in 1933, which though partly based on the Hypergon, added some additional negative elements inside the positive elements of the Emile von Hoegh optical formula, correcting the chromatic and spherical aberration to great extent, in such a way that it is even more related to the Double Gauss. Its symmetric scheme with only four elements turned it very sturdy regarding stringent tolerances in the production phase and also under harsh environmental contexts. It covered a large field of
view of 90º (clearly not so wide as the 135º Hypergon) and very small distortion values (though not so extraordinary in this aspect as the Goerz Hypergon, who has been the flagship in this regard and in maximum wide coverage for 110 years), so its global qualities including the chance of reaching maximum apertures around f/6.3 made him the standard Carl Zeiss large format aerial lens for approximately twenty years.

b) The 5 elements large format Bausch & Lomb Metrogon, designed by Wilbur Rayton in 1942 as a development from the Richter´s large format Topogon, adding a further element which achieved a flatter field and improved correction for astigmatism, though in the same way as the Topogon, it has a coverage limit of roughly 110º, so Hypergon with its almost 140º of coverage is unsurpassed as a super wide angle lens for all-around tasks, while the Topogon and Metrogon were created as aerial survey lenses. It is also related to both LF Hypergon and Double
Gauss, and in the same way as the Hypergon and the LF Topogon, it is a double meniscus type lens. In any case, Topogons and Metrogons alike with widest apertures around f/6.5 had to be stopped to between f/11 and f/16 to get a good image everywhere in the field, minimizing as much as possible the huge amount of oblique spherical aberration present at the widest diaphragm.

c) The masterpiece symmetric large format superwideangle Zeiss Biogon, featuring two menisci as frontal element and a very curved simple meniscus as a back element, designed in 1951 by the genius Ludwig Bertele, which had managed to create this optical scheme starting with the extraordinary Biogon 75 mm f/4.5 for large format cameras, following with Biogon lenses for 6 x 6 cm medium format Hasselblads and for 35 mm Contax rangefinder cameras. In all of them, two highly important aims were attained: a superb correction of the distortion very near 0, approaching Hypergon in this regard, and a fairly significant improvement of the contrast, it all
thanks to the extreme proximity of the back element to the focal plane.

d) The masterpiece large format super wideangle Wild Aviogon, designed by the genius Ludwig Bertele in 1952, which replaced both Richter´s Zeiss Topogons and Rayton´s Metrogons. It was an optical design getting both impressive resolving power of 100 lines/mm across the whole field and great contrast in 9 x 9" large format aerial cameras with for example the Zeiss Aviogon 152 mm . Therefore, it was clearly optimized for aerial photography and photogrammetry, so top priority was to achieve the least feasible distortion, in such a way that Bertele inserted two menisci in each extreme area of the lens, attaining an impressive figure of distortion lower than 10 microns on the whole image field, including the extreme corners of the negative. It is an entirely ten element new optical formula with a full 90º coverage, and its construction includes rare glasses and exceedingly thorough grinding for the time. Besides, the Wild Aviogon usually made in a focal length of 115 mm to cover a 18 square cm, and incredibly, it achieved 80% better
sharpness than the best previous large format super wide angle lenses, including at full aperture f/4.5, and it boasted a further valuable trait: it tackled with high marks the traditional brightness reduction toward the borders of the negative surface typical in former LF superwideangle lenses, to which it improved in this regard with a 300% more of brightness on the edges of the LF frame.


It quickly dawned on Hideo Azuma that his designing frontier was to strive after emulating as much as possible the German Carl Zeiss Topogon 25 mm f/4 following steps of the 1857 Schnitzer and Harrison Globe lens optical scheme (the first wideangle lens lacking distortion) taken to the limit by LF 1933 Richter´s Topogon, though it was clear from the very beginning that the downscaling of the new Nippon Kogaku superwide angle (the focal length of 25 mm was then deemed as that in the 35 mm format domain) would be a very strenuous and difficult optical toil.

Because of budget constraints of optical firms in the post II World War Japan and the need to use not very expensive glass to reduce designing cost, it was impossible to get professional image quality at full f/4 aperture, but there were two important advantages: on one hand, such a wideangle lens is generally used at f stops from 5.6 or even more often at f/8, and on the other hand the Topogon design, though not being a very luminous one, allows to obtain an extremely flat field boasting complete wiping out of astigmatism even using not the best and expensive glasses, and besides, it doesn´t need top-notch and also pricey antireflection coatings intended for the preservation of the glass from a chemical viewpoint as happens with other not Topogon modern wideangles in the range of 24/25 mm and featuring wider apertures of f/3.5, f/2.8, f/2, etc.


This way, Hideo Azuma devoted himself full blast to the designing of the W-Nikkor.C 25 mm f/4, with the only choice of doing his best to emulate the Zeiss Topogon 25 mm f/4 for Contax rangefinders, using the same optical formula of 4 elements in a symmetrical design means he had (that weren´t many, by the way, because he hadn´ t such good optical glasses as Carl Zeiss Jena in East Germany), optimizing the performance for f/11 and balancing as many factors as possible by means of hard work and a lot of tests, opting for maintain some coma, spherical aberration, some residual flare specially at the widest aperture and some chromatic aberration, in such a way that at full f/4 aperture the lens gets a simply acceptable resolving power and sharpness, becoming progressively soft towards the edges of the 24 x 36 mm negative, while a little flare appears on the whole image surface, even in the center, so albeit image quality could be defined as discreet to modern standards in terms of definition and contrast, it is utterly usable.

To eliminate the aforementioned little flare from the middle area of the negative surface, it is necessary to select f/5.6, which also brings about a betterment of the corners.

But when the W-Nikkor.C 25 mm f/4 becomes a good photographic weapon if we bear in mind its amazingly tiny size and weight, is at f/8 where there´s a visible improvement in definition and contrast (still a bit low to modern standards but enough) along with an elimination of flare to practical effects, and specially at f/11, where this lens reaches its pinnacle of image quality with a further fostering of sharpness before entering diffraction territory from f/16.


Though always a bit handicapped by the moderate contrast it delivers, the gradual changes between tones, hues and shades it renders is very good, to which a remarkable trait must be added: its behaviour as a very wideangle lens is peculiar and often images taken with it seem to have been shot from a longer distance with a 35 mm lens. In this regard (in spite of the very big differences in both mechanical construction and image quality), it resembles the Elmarit-R 24 mm f/2.8 when creating images with stunning perspectives but at the same time with such a naturality that there isn´t almost any perception that a super wide-angle lens is being used,
producing straight lines and faithful proportions on making pictures with impressive angle of view.

The charming W-Nikkor.C 25 mm f/4 sports some other traits to highlight, amongst them that it can be only focused by turning the focusing wheel, that the internal helical gyrates inside the objective barrel, the exterior barrel being fixed meanwhile, a bayonet front cap of special design for it, a deep rear cap also exclusively made for it.

The available diaphragms range between f/4 and f/22 and the minimum focusing distance is 106 cm.