Gossen Ombrux

Gossen Ombrux Exposure meter
	Gossen Ombrux exposure meter. The Ombrux was first introduced on the fair at Leipzig in 1933. It was the first Photo electric exposure meter build by Paul Gossen and marketed to the international market. The actual first meter was the Photolux however the name of this meter changed very shortly after introduction to Ombrux. With this meter he founded the Gossen company for light measure equipment which is still existing. The high price of the selenium element was a big problem to market the Ombrux meter for an commercial price on the market. However Paul Gossen solved this problem by deciding to start a production series of 100.000 exposure meters, so he guaranteed the manufacturer Electrocell in Berlin an order of 100.000 selenium cells. 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, 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 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. There are also meters without a film speed printed on the scale. Some meters have a different table printed on the aluminum plates. This table are a bit higher in sensitivity, the 9-10 DIN tbale is skipped. The table starts now with 12 - 13 DIN, 15 - 16 DIN, 18 - 19 DIN and the last one is 30 Scheiner. 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) 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 forestry to measure the amount of light in the woods for growing young trees. If you buy an Ombrux on Ebay, very often the meter is not 100% but has little damaged or is damaged very heavy. Don't forget, these meters are some 77 years of age for the oldest ones (2010) and were made to take with you when going out to take pictures. Very oft they did not had an easy life. Or even somebody has tried to fix the meters with even worst results. To get them in proper shape, you need to do some repairs on these objects. Therefore you also needs spare parts to replace damaged or broken parts and these parts are not on the market any more. This means that you need donor meters to get your collection items in good shape again.

	Technical data:	06.15.2010
	Manufacturer Name Introduction Sensor Measurement Application	P. Gossen & Co, Erlangen Germany Ombrux 1933 Selenium photo cell reflected light Photographic / Cine
	Film speed Angle of measurement: Dual scale read_out: Black scale sensitivity multiplier Aperture range Exposure time	15/16 DIN = 23 Scheiner 45° vert. 75° horizont. 1/10 sec ~ 1/500 sec 1/10 sec ~ 30 sec. 40 times f/ 9 or see table 1/500 ~ 30 sec.
	Size Weight Power	60 x 75 x 28 175g. with case 245g. None


Ombrux and Blendux Exposure meters. Sold by J.H. Dallmeyer Ltd. 31 Mortimer street London W.1. These meters, one calibrated with exposers for the still worker, and the latter showing lens apertures for the cine people, are of the type employing a photo-cell and requiring no batteries. The meter is merely pointed at the subject and the dial reading noted. the point which will appeal to photographers is that there are here reliable meters of this type at the low price of £4. 4s. Another point in their favor is the light weight and compactness. The "Blendux" when folded in his leather case, takes up no more room than a 100-foot reel of film. In use, the angle of view is stated to be 45 deg. vertical and 75 deg. horizontal. Another feature is the provision made for use in weak light. By pressing a button the meter reading is multiplied forty times, and the correct reading can be taken from an alternative dial. Both meters are supplied with slip-in tables printed on metal, by means of which the exposures at other apertures and other plate speeds can readily be seen, or, in the case of the cine meter, the apertures for other camera speeds and other types of film. we think these meters should prove popular.














		From "Tectona, uitgave der vereniging van ambtenaren bij het boschwezen in Ned. O. Indie" This is a fragment from a article by the Dutch forestry in the Dutch indies about the amount of light coming trough the top leaves of the trees and falling on the ground by a certain condition.For this measurement the Ombrux is used.
		The result of the light value multiplied by the time is constant over the whole scale and is close to 50 Lux-seconds. A reciprocal of the reading of the scale multiplied by 50 is the value in lux. By a reading of 1/100 sec, is equal 100x50= 5000 lux or a reading of of 5 sec. equals 1/5x50=10 Lux.
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