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Minox enlarger 25401
8 x 11 mm negative enlarger · Model II 25401

Especially for their range of subminiature cameras — that recorded images onto 8 x 11 mm film — Minox produced accessories that allowed spies and secret agents to develop their own films and print the photographs in a makeshift lab, rather than bringing them to a regular photo shop.

The unit consists of a heavy die-cast frame with a 400 x 330 mm horizontal table at the bottom. Behind the table is a canted vertical column that holds a projector that can be adjusted vertically.

The projector consists of a lens (here protected with a plastic cap), a negative holder just above it, and a lamp at the top. When connected to the mains and switched on, the lamp causes the 8 x 11 negative in the holder to be projected onto a fresh piece of photographic paper that is placed on the table. By altering the projector height, the size of the print can be determined, whilst the lens should be adjusted for optimum sharpness.

The device is enabled with a power switche that is mounted inline with the power cable. Further­more, a toggle switch mounted at the base, provides two levels of brightness, of which the brightest setting is used by default. Inside the dome is a 6V car lamp with bayonet fitting, that is powered by a 110/220V transformer mounted in the base, below the black horizontal table.

The enlarger shown here was in production from 1971 to 1987, during which time 3044 units were made (serial numbers 17291 - 20334) [1]. In all, about 19145 Minox enlargers were made.
  
Minox enlarger for 8 x 11 mm film

Minox enlargers were very popular among hobbyists as they no longer had to find a specialised photo lab to print their photographs, but also in the espionage trade, where it was mandatory to keep the information from prying eyes. Especially for a non-disclosed American agency – most likely the CIA – Minox made a special version (actually a reducer) for the creation of microdots.

Minox enlarger for 8 x 11 mm film
Minox enlarger for 8 x 11 mm film
Close-up of the projector
Brightness switch mounted in the base
Lens
Projector seen from the rear
Removing the lens assembly
Power switch
Serial number plate
A
×
A
1 / 9
Minox enlarger for 8 x 11 mm film
A
2 / 9
Minox enlarger for 8 x 11 mm film
A
3 / 9
Close-up of the projector
A
4 / 9
Brightness switch mounted in the base
A
5 / 9
Lens
A
6 / 9
Projector seen from the rear
A
7 / 9
Removing the lens assembly
A
8 / 9
Power switch
A
9 / 9
Serial number plate

Features
The diagram below provides a quick overview of the features of the 25401 enlarger. At the left is the sloped shiny vertical column, on which the movable die-cast section with the projector is mounted. The projector can be moved up or down by pressing the release button at the bottom.
Click to see more

A strip with a number of 8 x 11 mm negatives can be placed on the film holder, after which the pressure lever should be lowered in order to keep the negative in place. Two diffusors – mounted at different heights – ensure an evenly illuminated image. For cleaning, the lens assembly can be removed by pushing down the release button and pulling the assembly out towards the front.

Projector seen from the rear
Removing the lens assembly
Lens assemble seen from the top
Lens assembly seen from the bottom
Light bulb mounted inside the dome
First diffusor
Lamp plug
B
×
B
1 / 7
Projector seen from the rear
B
2 / 7
Removing the lens assembly
B
3 / 7
Lens assemble seen from the top
B
4 / 7
Lens assembly seen from the bottom
B
5 / 7
Light bulb mounted inside the dome
B
6 / 7
First diffusor
B
7 / 7
Lamp plug

Known models
Model Type Production S/N Remark
I - 1950 - 1951 100 - 791  
II 2201 1951 - 1963 1000 - 10088  
II 2201 color 1951 - 1963 Colour version of the 2201
II Microdot 1960s ~ 80 units Built for US agency 1
II 2203 1963 - 1971 11001 - 17290  
II 2202 color 1963-1971 Colour version of the 2203
II 25401 1971 - 1987 17291 - 20334  
II 25501 color 1971 - 1987 Colour version of the 25401
II ? Late 1990s 30 Completed from parts
  1. This version is actually not an enlarger but a reducer, as it was used to shrink the 8 x 11 mm negatives to microdot size. The images were transferred to special emulsion microdot film [1].

Documentation
  1. Minox enlarger Model II, Operating Instructions
    Minox GmbH, Giessen (Germany), July 1962.
References
  1. Submin, Minox 8 x 11 - enlargers
    14 January 2008.
Further information
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Crypto Museum. Created: Wednesday 25 September 2019. Last changed: Monday, 30 September 2019 - 15:10 CET.
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