The R77 light meter is capable of reading luminance from 1 0 to 1,000 footcandles (fc).
Before you begin, remove the 10X multiplier plate
from the lens.
Because display screen luminance typically ranges from 10 to 50 fc, take readings from the bottom scale only.
Light Meter Setup - 3
To measure a display screen's luminance,
1 Set the scale switch to the bottom position (to set up the 10-50 fc scale).
2 Place the lens against the middle of the screen and read the bottom scale.
Note: When the light meter is not in use, slide the scale switch to its top position, and store the meter in its protective case.
Important: If you suspect the light meter is giving false
Light Meter Setup - 4
readings, verify the readings with a known-good light meter or photometer. Also check the age of the R77 light meter by its four-digit manufacturing date stamp (such as 0398 for March 1998).
Caution: Dropping the meter can permanently damage its accuracy. A shock-damaged meter might read incorrectly or its pointer may not drop to zero.
1 Press the red button on the back of the light meter. If the reading is
_Read out of the red area,
Button replace the battery.
2 Move the side switch to its lower position so that the scale reads 2 through 10.
3 Uncover the lens of the meter.
Place the lens against the middle of the screen and press the read button to read the scale.
1 Remove the metal slide, if installed, from the top of the light meter.
2 Install the white lens with the red dot.
3 Rotate the swivel head so the lens of the meter faces the monitor.
4 Place the lens against the middle of the screen and read the scale.
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