Actinometer light meters
 

BRIEF DESCRIPTION OF The WYNNE ACTINOMETER
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Between 1893 and 1938, George Frederick Wynne formed the Exposure Meter Company in Wrexham, UK to manufactured an early form of actinometer (light meter) called "Wynne's Infallible Hunter Meter". This was one of several on the market at that time.

It used a photo-sensitive paper which changed colour to a dark grey tint. The photographer would match the colour agains a swatch on the Meter and then record the time taken for this to happen; this was called the "actinometer time".

The photographer would map the actinometer time to the Meter's circular disc to select a suitable lens stop and shutter speed for the exposure.

Basically the photo-sensitive paper was the equivalent of a selenium cell and the circular disc was like the calculator of a Weston light meter.

MY QUESTION
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The photo-sensitive paper is no longer made and I can't find a description of how it was made. Does anyone know or have information on what it contained or how it was manufactured?

The Denbighshire Archives hold copies of his patents.

Thanks Michael. I'm chasing that up with the archivists.

You may try simple b/w paper. It gets brownish or magenta depending on the type if exposured. May be it is sensitive enough.

You need new tables, of course.