Marked "Congress of Paris 1900". In use the light is measured in the normal way. The meter carries scales - F/n for f numbers and plate speeds; T for shutter speed and actinometer value. The number of the plate speed in column F/n is set against the actinometer value. The shutter speed and aperture pairs can then be read.

Made in Germany.

In use the actinometer time is found by exposing sensitive paper and matching against a standard tint. A ribbon is then moved to align the plate speed with the actinometer time. The shutter speed and aperture pairs can then be read. Six columns of shutter speed are given for different classes of subject. The meter card is contained in a cover which carries a conversion table of Smith plate speeds to Scheiner, H&D and Warnerke. A table of shutter speeds to stop motion is also shown.