Sekonic L-398M specification

2.Lumidisc. Employ for illumination contrast Adjustment and luminance measurement.

∙Contrast measurement

a. Mount Lumidisc
sensor	Install in the same

manner as Lumisphere.

b. Hold meter at subject position and point Lumidisc

directly toward center of main light.

c. Press stopper button

read meter scale footcandle indication

d.Turn the memo pointer dial and set the pointer 1 7 at the footcandle value the needle points to

e.In the same manner, measure the fill-in light. In this case, use care that light from main source dose not enter sensor.

f.Read a difference between the footcandle value the pointer is set (see above c) and the one for fill-in light (= needle position.

Ratio between main and fillip light footcandles becomes the contrast ratio.

Example: With main light at 640 footcandles, fill-in light reads 320 footcandles. Illumination contrast ratio becomes:

640	2
320	1	or 2 : 1