Zeiss Ikon Contax I 1932-36

Tomei Collection

The Zeiss Ikon company announced the new Contax camera in the Spring of 1932. This immediately launched a new level of competition between Zeiss Ikon and Leitz who was about to release their Leica II(D). Both cameras had sophisticated coupled rangefinders and a variety of lenses and accessories for both amateur and professional.  However, that's where the similarities end because ZI's approach to design of their shutters, optics and ergonomics differed sharply from that of Leitz.


The history and importance of the Contax cameras cannot be fully appreciated without considering the contributions of Hubert Nerwin, the chief designer at Zeiss Ikon until he eventually moved to Eastman Kodak in 1955.  Nerwin had several hundred patents issued regarding a wide variety of camera designs (Right: A 1940 patent for a viewfinder design showing a camera that closely approximates that of the Contax models).When the Contax was introduced (later to be called the Contax I), it was plagued with problems largely attributable to the fact that it had been brought to market prematurely and proved to be an embarrassment to the company.  Nerwin improved the later version of the Contax I particularly with respect to the operation of the rangefinder.  His many further improvements in design were incorporated into the Contax II and III models.


Collectors note that the Contax I has at least seven distinct variants between 1932 and 1936, whereas later Contax models do not.  This is a reflection of the early design problems which were successfully addressed by Nerwin.  The Contax I(f) example shown here is among the later production models that benefited from Nerwin's improvements.  These include the newly designed rotating prism rangefinder that also appeared in the Super Nettel and Ikonta models.  It is considered to be the most reliable variant of the early Contax cameras.


The earliest Contax incorporated a very precise rangefinder design that utilized a fixed beam-splitter on the prime axis and a pivoted mirror on an oblique axis separated by 31/2 inches.  This design theoretically provided for much more precise measurement of distance compared to shorter based rangefinders in cameras of competitors such as the Leica from Leitz.  However, the design required that the pivoted mirror rotate within a rather small 3 degree arc and the precision of its performance was therefore necessarily limited to the precision of the mechanical coupling.  This limitation would soon be addressed in the subsequent rotating optical wedge design that Nerwin first introduced in the Super Nettel and the Contax I models soon thereafter, in which the mechanical coupling rotated the wedge a full 180 degrees between infinity and three feet.


Lipinski (see Fig. 4.78 on left from 1955) presents a detailed analysis of the Contax rotating prism rangefinder design that was introduced in 1934.  He comments that the design is not inherently superior to that used by Leitz which also used a rotating prism in place of a pivoted mirror.  However, the use of two rotating biased-cut closely coupled prisms presumably further reduced the problem of dust by having the entire optical path within glass (the Leica design used a prism essentially as a mirror and an open optical path).  None the less, it was the opinion of many optical engineers at the time that the Contax design was specifically calculated to simply avoid conflict with dominant Leitz patents.  Therefore, with the existing production tolerances of the precision gears, it was significantly more accurate to use a rotating wedge than the pivoted mirror design though not significantly different from that of the Leica.  Although the rotating prism design was excellent, Nerwin's group at ZI had a further improvement in the works which permitted matching the rangefinder view to that of a normal lens.  That design was to be called the "sliding wedge prism" and was to appear in the Contax II and III in 1936.


Nerwin was a very prolific and creative engineer and had actually designed a special coupling between the viewfinder and lens mount to permit automatic matching for a series of lens focal lengths (as seen in the patent drawing to the right).  This feature never went into production at ZI, though, presumably due to the increased cost.  A similar lens coupling would appear in the Leica M models about 15 years later.  To accomplish the same thing the Kodak Ektar, introduced in 1941, would incorporate a manual optical adjustment in the combined rangefinder/viewfinder window to match the field of lenses of different focal lengths.

Hubert Nerwin's first major challenge was to correct the problematic design of the early Contax I model. This camera is a particularly fine example of the final variant of the Contax created by Nerwin (called Contax If to distinguish it from the six earlier variants and the II and III). In the two later variants that incorporated the rotating prism rangefinder instead of a pivoted mirror, the viewfinder window had been moved to the outside to accomodate the change in the internal rangefinder optics.  This camera was built about 1934, serial number Z26379, and has matching numbers on both the body and removable back.  A 5cm f/2.8 Tessar collapsible lens (Nr. 1427624) normal lens is mounted and is the correct black nickel-plated model for the first Contax cameras.

There are two examples of the early chromium-plated universal viewfinder shown, Nr. 802 and 3673.  Nr. 802 represents the earliest built by Zeiss Ikon and does not have the détentes (clickstops) that were added soon after production began in 1932.  The 433/24 Albada sport finder is shown above.  This is the earliest version which was available only in black and intended solely for the 5cm lens.  The 433/26 available later included framing for both the 5cm and 13.5cm lenses and was available in either black or chrome.

In addition, a 13.5cm f/4 Sonnar lens is shown that was built in 1934 (Nr. 1589727).  These early lenses have black enameled faces and nickel plating.  Later, Nerwin changed the designs and began using chromium plated bright metal.










Of the seven distinct variants of the Contax I, the last is the If as described by McKeown as being most easily recognized by the four screws holding the accessory shoe.  However, Nerwin had made a number of changes to the internal mechanisms most notably in the rangefinder.

Although a Contax I is rarely if ever a fake since it is significantly different from the later models, many have been reassembled from parts of incomplete or damaged examples.  These invariably have been repainted with varying degrees of care and often will have serial numbers on the body that do not match that on the rear door.  In addition, the white paint used on the front will be new though it may have an old and worn look.  Here is a 25X magnification of a portion of the front lettering on the camera shown here.  Note that the green copper oxides from the underlying brass have mixed with the original white paint, evidence that the camera had not been repainted.


Zeiss Bumps

Many of the early Contax I model have serious corrosion beneath the leather cover.  This example arrived with rather bad "Zeiss bumps" on the rear door which necessitated careful removal of the leather in order to remove the oxides around the brass rivets.  Before re-attaching the leather cover, each rivet head was covered with a small amount of clear lacquer to help reduce the further oxidation.

I do not recommend that the leather be removed on the remainder of the body.  The rear door covering can be softened easily by soaking with wet cotton pads followed by careful pealing with the help of a razor blade.  The leather is not damaged by the wetting but will stretch quite a bit.  After preparing the metal surface and blotting dry the damp leather, it is coated with a thin layer of white glue.  This allows for repositioning the leather as it dries and the leather slowly shrinks to fit.  I strongly recommend against the use of any contact cement that is not water soluble.  I would more strongly advise against cutting the leather over the bumps to remove oxides since the leather will be permanently marred.  Bumps in the vicinity of the front control knobs are simply tolerated.


 Early Zeiss Ikon Film

It is quite rare to find an unused 35mm daylight cassette refill (Tageslicht Kassettenfüllung) from the early 1930's.  When I first found this roll, I was curious about  its age.  It was produced for the first Contax which appeared in 1932 but I was unclear as to how long the film had been sold in a simple green wax paper wrapper.  According to the helpful people at Zeiss Ikon, these early refill cassettes were indeed simply wrapped in green wax paper.  In 1934 Zeiss Ikon film was available in multiple grades and packaged in the more familiar individual boxes.  So this dates the film shown here to 1932-34.