Densitometer for photography

A densitometer for photography comprising:

• a disk on which are disposed at a predetermined circumferential spacing filters of three colors for measuring the transmission density of a negative film, filters of three colors for measuring the reflection density of a color print and for measuring the transmission density of a color reversal film, and a visual sensitivity filter for measuring the reflection density of a monochromatic print, a transmission density of a monochromatic film and a transmission density of a monochromatic reversal film;
• a lamp for enabling the measurement of the reflection densities;
• a lamp for enabling the measurement of the transmission densities;
• a light-receiving element;
• a motor for rotatingly driving said disk as to bring the seven filters into alignment with said light receiving element in a one-by-one fashion;
• a density measuring portion for measuring the density from the output of said light-receiving element;
• a density difference computing means for determining the difference between the measured density and a reference density stored in a memory of a computing processor;
• a color-key correction value computing means for computing a color-key correction value from said difference;
• a density-key correction value computing means for computing the density-key correction value from said difference;
• an exposure time correction factor computing means for computing the exposure time correction factor from said color-key correction value;
• a display means for displaying the computed color-key correction value, density-key correction value and the exposure-time correction factor;
• and
• an interface for externally outputting the data concerning these values and factor.