Old Delft Minor 3.5cm f/3.5

Old Delft Minor 3.5cm f/3.5

The Old Delft Minor 3.5cm f/3.5 is a compact Dutch wide-angle lens produced around the end of the 1940s by De Oude Delft, usually known internationally as Old Delft. It was manufactured in original rangefinder-coupled versions for both Leica Thread Mount and Contax RF cameras.

The two factory mounts share the same Minor model identity and reported four-element, three-group Tessar-type optical construction. They are therefore covered by a single profile. The LTM version has its own focusing helicoid and rangefinder cam, while the Contax RF version uses the external bayonet together with a complete focusing assembly and rangefinder coupling.

Surviving lenses are usually chrome or silver finished and use a comparatively heavy brass barrel despite their small dimensions. Published weights of approximately 128 to 134g appear to describe LTM examples. The exact dimensions and weight of the Contax RF barrel should not automatically be copied from the screw-mount version.

The lens focuses to approximately 0.9 metres. Original examples were often supplied with a matching Old Delft 35mm external finder, recognised by its long, rounded or bullet-shaped housing.

Optical qualities

Rendering

Specialist references identify the Minor as a four-element, three-group Tessar-type lens. This construction provides a compact barrel and comparatively strong central definition, particularly when the lens is stopped down.

At f/3.5, contrast and outer-field sharpness can be lower than in the centre. Stopping down improves overall uniformity. No sufficiently controlled comparison between the LTM and Contax RF versions has been located to support a mount-specific difference in rendering.

Contrast and coating

Surviving Minor lenses are documented with lightly coated optics. Contrast is moderate by modern standards and depends strongly on coating condition, internal cleanliness and element alignment.

Strong light can produce veiling and loss of contrast. A suitable hood is useful, although original Old Delft accessories are now uncommon.

Distortion and vignetting

The simple Tessar-type construction can show some light fall-off at maximum aperture. Distortion appears modest in surviving user examples, but no reliable factory figure or controlled measurement has been located. Numerical distortion and vignetting values should therefore remain unlisted.

Sample condition

Separation, haze and cleaning marks are regularly mentioned in auction descriptions. These age-related problems can have a greater effect on image quality than any difference between the two original mount versions.

History

Development and Launch

De Oude Delft was a Dutch optical manufacturer based in Delft. Its photographic products form only a small part of the company's broader optical output, making surviving interchangeable camera lenses comparatively uncommon.

The Minor 3.5cm f/3.5 appeared during the immediate post-war period. Documented factory examples include an original rangefinder-coupled M39 lens from approximately 1949 and several Contax RF examples from approximately 1950.

Factory Mount Versions

The Leica Thread Mount Minor was produced as a complete factory rangefinder lens rather than as a later conversion. Leitz Auction documents serial number 486587 in an original coupled Leica screw mount.

Original Contax RF examples are also firmly documented. Serial number 503635 was offered as a factory Contax lens, while serial number 5035730 came from the holdings of the Old Delft museum and was specifically described as rangefinder coupled.

These documented examples confirm that the Contax RF lens is an original production version of the Minor, not a later adaptation of the M39 barrel.

Production Evolution

The known production period appears to have been short, approximately 1948 to 1950. Available evidence does not establish a significant optical redesign during this period.

Minor differences in engraving, focusing scale, coating and barrel construction may exist. These should be recorded as production variations unless a different optical or mechanical specification can be demonstrated.

Collector Notes

The Minor is uncommon in either mount, with the Contax RF version appearing particularly infrequently. Originality of the focusing mount and rangefinder mechanism should be checked carefully.

Collectors should inspect the optics for haze, separation, coating wear and cleaning marks. The brass barrel should also be checked for stiff focusing, loose fittings and damage to the rangefinder cam or bayonet.

The matching Old Delft finder, original caps and cases add collector interest, but their absence does not indicate a different lens version. Because many surviving lenses have been serviced, the serial number and construction should be documented before restoration.

Special editions

No separately catalogued factory special edition is confirmed. The original LTM and Contax RF lenses are regular factory mount versions of the Minor rather than special editions. Differences in coating, engraving or included finder should be recorded as production or accessory variations.