Gossen Ombrux exposure meter

Update: 05.11.2012

Gossen Ombrux exposure meter.

The Ombrux exposure meter was first introduced on the fair at Leipzig in 1933. It was the first photoelectric photographic exposure meter made by Paul Gossen and marketed to the international market.
Their actual first meter was named Photolux however the name of this meter changed very shortly after introduction to Ombrux. With this meter he founded the Gossen company for light measuring equipment which is still existing.

The high price of a selenium element was a big problem to market the Ombrux meter for an commercial interesting price. However Paul Gossen solved this problem by deciding to start a production of 100.000 exposure meters, so he guaranteed the manufacturer Electrocell in Berlin an order of 100.000 selenium cells, in this way Electrocell was able to deliver the selenium cell to Paul Gossen at a price of 7.50 Reichsmarken.

At the time of the fair, Paul Gossen was able to offer the Ombrux for a price of 29.50 Reichsmarken excluding the leather case. The question was only if the time was right to offer the photographic market a meter instead of the old ways to make the exposure.

At the same time, Weston brought a meter on the market in the USA but this was a very expensive equipment. On the same fair in Leipzig was another company who brought a likewise meter on the market, Metrawatt a company from Nurnberg and founded by Dr. Siegfried Guggenheimer. 

With the Ombrux, photographers could measure actually the light instead of estimate the light value by experience, use of the not so reliable aktinometer or use of tables like the one made by Paul Dette. The Ombrux was made for photography while his counterpart the Blendux was made for cine purposes.

The meters from the type Ombrux always have a scale with exposure time value in seconds. The types do differ, some have only the plate / film speed in Scheiner were others have the Scheiner scale combined with DIN value. In most cases the value is 23 Scheiner, 15~16/10 DIN. The film speed seems relatively low but in that time this was the regular filmspeed.

The measuring element is a selenium photovoltaic cell and the big lens on the front was taken from a flashlight manufactured in that time in Germany. The case holds some aluminum plates with correction tables in DIN and the older German value: Scheiner. Also known is a version made for Leica, with Ombrux f. Leica printed on the scale. (see photo). The big difference is here the adoption of the scale to the Leica aperture and exposure time values.

With a little formula, the Ombrux can be used as a light meter instead of an exposure meter. By taking the reciprocal of the value and multiplying this with 50 you will get the light value in lux. See on the bottom of this page for an example of this formula.

Except for Photography, the Ombrux was also used in the agriculture sector like in forestry, to measure the amount of light in the woods for growing young trees.

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