The Diaphot was an extinction meter. It was offered by ICA and later Zeiss Ikon from 1921 to 1934.
From 1936 to 1940 it was offered in a slightly modernized style. Even the modernized model bore the star logo of ICA
The meter has a viewfinder on the back. You look into the finder and see the motiv through a blue filter. By turning the outer ring of the Diaphot the filter grows lighter or darker. When the black and the grey parts of the motiv have only one colour, this is the right setting. Now you can read time and aperture settings.
Links[]
- Diaphot in Ollinger James' Light Meter Collection [1]
- model of 1936 in Reinhard Krahé's Krähenseiten [2]