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"DREM" Justophot , Austria

Justophot Exposure Meter
(An extinction meter)

Emil Mayer, born in Böhm 1871, is one of the forerunners of modern photography. He took most of his pictures of an urban scenery. His occupation was an attorney and a photographer but besides he was an inventor. One of his seven patents is this optical light meter "Justophot".

I have tried to resolve how it works but still I am not totally aware of its function. In the manual is written that the use "seems" complicated but despite the fact it is simple. You have to look towards the object through the meter and turn a ring until you cannot anymore see the back lighted numbers inside the meter. At this position you can read the proper adjustments. The extinction meter, as this is, will only give a correct answer if you have been in the same light conditions for a couple of minutes. When looking through the meter you have to read the numbers quickly rather than peer at them for a long time as otherwise the eye adjusts to the light.

Pretension that you get absolutely and scientifically correct exposure values seems to be a bit exaggerated, similar to those we are accustomed to see in TV-Shop commercials.

"Drem", which is the manufacturer, was an Austrian company in Vienna. Austria has a long and famous tradition in high class optical and mechanical industry. Remember such brands like Swarovski and Eumig.

"Using Justophot seems at first quite complicated but you find it as simple as possible after you have briefly acquainted with it.

Justophot has several parts which are turning separately. Explicitly: An innermost tube, dial tube, An outer tube, magnifyin glass tube, that could be pushed back and forth by the aperture ring. If you look inside the meter, you see a matte glass and behind that is an adjustable iris diaphragm. On the beveled side of the diaphragm ring you can see a marking which slides ower a normal diaphragm dial..." etc.

Actually, you compare certain digits inside the meter and the "chip" is between your ears.


Selenium cell has a special feature. It produces electricity when it is illuminated. More light brings more electricity. This means also that any battery is not needed. Something about selenium exposure meters on this page.

©2004 Reijo Lauro