Practos extinction calculator
circa 1930
Milner extinction calculator
Heyde's Aktino-photometer
Degen Photo-metre normal exposure calculator
1900-1910
Practos Exposure Extinction Meter and Case.
Eios aktinometer extinction meter
Zeiss Ikon diaphot meter. Watch pattern extinction meter in case
circa 1925
Heyde's Aktino-photometer
1905-1935
Heyde's Aktinometer. Extinction meter for use on camera ground glass screen
circa 1914
Ica Diaphot extinction calculator
Ica Diaphot Extinction Meter
Drem Leica extinction calculator. Drem Zentrale
circa 1930