Gossen Sixtomat Exposure meter
 





 

Sixtomat exposure meter.

The Sixtomat, manufactured  by Gossen in Erlangen Germany, is a exposure meter  to be used for photographic and cine purposes. The meter only measures reflected light. The sensor can be shut off for light by a metal rolling blind. This roller blind protects the sensitive parts of the meter like the sensor and the glass of the reading scale. The blind is made  of special V2a rustles steel.

The Sixtomat has been made in different versions and also in different colors. Most common is the black version rare are the dark blue and dark red versions. The first production date is around 1950 and since then a large number of these meter have been made. Later on this meter has been improved and merged into the Sixtomat J the Sixtomat X2 and the Sixtomat X3. There are some minor differences in the production versions like the color of the scale on the film sensitivity knob and the knob itself. The meter has been developed shortly after the Sixtus 2. The Sixtus 2 is the first post WW2 meter since 1936. The Sixtomat is a complete new design after the well known bakelite versions.

An application for the German patent was done on December 24 1949, the USA patent for the Sixtomat was requested at June 2 1950 by P. Gossen & Co. GMBH Erlangen Germany under number 2,699,087. The inventors are the son of Paul Gossen, Hans Gossen and Erwin Pfaffenberger. 

In December 1950 the American Cinematographer has placed an article in their magazine presenting this meter;  "Sixtomat. New, Automatic Exposure Meter." The Sixtomat is being imported and distributed in the USA by the Mitropa Corporation, New York City and the retail price in that time was about US $32.50. This article describes the function of the meter extensively.

It is clearly an automated version of his predecessors, the Photolux, Ombrux, Blendux, Cimbrux,  Sixtus, Ombrux 2 and Sixtus 2. The red button for changing the sensitivity of the meter is now incorporated in the mechanism. When rotating the knob, you can see the scale changing from red to black or vice versa. A internal switch changes this sensitivity accordingly, replacing manual pressing the button. It is a meter of the next generation of Gossen exposure meters for photographic and cine purposes, measuring reflected and incident light (some of them) by use of what Gossen called the 'rollo' a movable blind. The electrical function of the Sixtomat is still based on the older predecessors with the red button on top. This button enables the meter to measure with different light sensitivity. This function is incorporated into the Sixtomat but invisible for the user because it is mounted on the axle were also the knob is mounted. The sensitivity changes when the scale goes from black to red and vice versa. In the newer versions of the Sixtomat this function has been removed. The notch on the axle is still there but the switch has been removed at the same time the metal roller blind has been replaced by a diffuse one enabling the meter to measure reflected light en when the blind is in front of the sensor. also to measure incident light.

The first Sixtomat exposure meter, from the early fifties and still available in the early seventies so it last for more than two decades. In a Gossen brochure from 1971 it still available and in the meantime, more than 1.500.000 meters have been produced. The types that are manufactured are as far as we know the Sixtomat, the Sixtomat X2, The Sixtomat X3, the Sixtomat Deluxe I, the Sixtomat J. Even between the meters of the same type, there are differences in manufacturing. Also there are meters made in different colors but of the same model, like the Sixtomat normally in black is also in dark blue and even in dark red. The Sixtomat X3 has been made with a complete transparent housing.

There are several versions of the Sixtomat from 1950 to the 1970th onwards;

Sixtomat, first Sixtomat with metal roller curtain only for reflected light.
Sixtomat, as above but with a 'L' on the read out scale for Leica.
Sixtomat-I deluxe, the metal curtain has been changed to a plastic one enabling measurement of incident light
Sixtomat J, still figuring out what exactly the differences are
Sixtomat Dual,
Sixtomat X2, predecessor of the Sixtomat X3 except for the color finder
Sixtomat X3, Final Sixtomat for measuring reflected light, incident light and color temperature. Sold until the seventies.
Sixtomat X3, version in a transparent housing
Sixtomat X3 with 'Tower' label',  version for Sears.

See versions for an overview.

Special thanks to Richard W Holzman and Simon Spaans for additional information and articles.
 

  Technical data:

06.13.2010

 

Manufacturer
Name
Introduction
Sensor
Measurement
Application
P. Gossen & Co, Erlangen Germany
Sixtomat
aprox. 1950
Selenium photo cell
reflected light only
Photographic / Cine
  Film speed
Angle of measurement:
Aperture range
Exposure time
Cine
6 - 400 ASA / 9 - 27 DIN
Reflected light °
f/ 1.4 ~ 45
1/1000 ~ 30 sec.
8 ~ 64 fps
  Size
Weight
Power
76 x 59 x 29 mm.
180 g.
None
   
 
 
 

 
 

It seems that also at Gossen things can be behind repair. The meter from the customer has been replaced by a new meter wit serial number S53635 by Gossen in Erlangen.

This meter was for sale on Ebay and is a nice extension for the collection especially were the meter is in very good condition and full operational. the delivery date is February 28 1952 and the customer has complained on the 24th. so the meter was already defective for that date. This means the Sixtomat was available before Feb. 1952.

 
  Version with a white painted read out scale instead of an aluminum one and without the 24 FPS on the scale
 
  Different versions of the sixtomat; left, with a plastic film speed knob and a black scale. Middle with a plastic film speed knob and a silver scale. Right with a metal films peed knob and a black scale.
   
        
USA Patent 2,699,087
       
 
Exploded view of the Sixtomat
 

This meter is from mechanical point of view a very nice piece of equipment. Most parts are made of brass and very precisely manufactured. The application for the USA patent shows the drawings of the meter, the electrical circuit and the description.

The red button on his predecessors has been replaced by an internal rocker switch connected to the knob also turning the scale. During the red phase of the scale, the switch opens giving the meter a higher sensitivity. This is done by disconnecting a resistor that is connected parallel over the sensor giving the meter more power coming from the selenium photo cell. This switch has been removed from later versions.

     
  Gossen Sictomat manual in Dutch
 
  Gossen sixtomat manual in German
 
 
Brochure Sixtomat in German
   



How does the Sixtomat works?

If we take a look on the picture on the right side, we see a Photoelectric cell (6). As soon as light falls on this cell, a voltage is generated.  As a result of this voltage, a current runs trough the meter (7) causing the meter to the right (more current)

On the meter on the left, we see a cylinder with red and black markings. As soon as we turn the knob on the side of the meter we change the position of these markings. On the axel of the cylinder is a little notch (10) which opens or closes a contact between the points 26 and 27.

if the contact is closed, we place another resistor parallel with the meter. Because the meter itself also has a resistance, we place 2 resistors in parallel causing the current to run trough both resistors. This makes that there is less current trough the meter so the meter, causes the meter moving to the left (less current).
 



       
       
 
 
  Sixtomat meters from the collection of Simon. A, Spaans. These are two black versions and one very dark blue version.
 

Copyright © E. van der Aa 2010, All rights reserved.