Abstract
There is a need for luminance meters in various fields of photometry having these characteristics: a- objective method of measurements. b. variable shape and size of measurement area. c- absence of parallax during aiming operations. d- Possibility of observing the part of the field of view to be photometer and its surrounding before and during measurement. e- correction for various spectral compositions of the light. f- possibility of reading during measurement. g- simple calibration, and h- interchangeable optical system.