The scales on the Director series are in footcandles. Thus primary designed to measure ILLUMINANCE! With the slide out it will read directly in footcandles, with the high slide in you have to multiply the numbers with 30 and read as footcandles. Please note position of the lightmeter pointing at Camera. Illuminance is always measured from the subject to camera position!

ILLUMINATION, ILLUMINANCE lumens/m² = lux (lx) lumens/ft² = footcandle (fc) lumens/cm² = phot (ph) illumination = lumen/area = I Cos(a)/ r² 1 lux = 10.76391042 footcandle 1 footcandle = 0.09290304 lux where: I = candles = luminous intensity r = distance from surface to point source a = angle between the direction of the flux and the normal to the surface For example, how many lumens pass through a spherical area of 240 cm² that is part of a sphere 20 cm in radius when a point source of 100 candles is at the center? Since 100 candles is 100 lumens/steradian, and one steradian for this sphere has an area of 20cm x 20cm = 400 cm², the area in question is 240/400=0.6 steradians, and the number of lumens passing through is 0.6 x 100 = 60 lumens.

Example of a calibration card...

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