Toronto. Another popular design to aid the photographer in his pursuit of the correct exposure was the extinction meter. This device relied on the photographer looking though an eyepiece or tiny aperture as a filter was slowly moved across the field of vision until it was extinguished. A dial or table would convert the just extinguished reading to a choice of aperture and speed based on the plate or roll film being used. A small insert lists the various plates and films of the period and the suggested corrections to use.
In 1921 ICA in germany created the elegant Diaphot. This slim watch shaped meter used a blue filter and a wedge that could be rotated across the field of view until the scene shadows just disappeared. In 1926 ICA was merged into the newly formed Zeiss-Ikon group in an attempt to rationalize the German camera industry. Larry Gubas (editor of Zeiss Historica and president of the Zeiss Historical Society) describes the merger in his excellent and massive book “Zeiss and Photography“.
Gubas states that after the merger ICA became the accessory maker for all the Zeiss Ikon companies. The Diaphot ICA created was rebadged Zeiss Ikon (as is mine) and continued manufacture through 1934. From 1936 to 1940 a more modern version was manufactured and sold.