Model R

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.

Three scales are shown on the light meter:

  • 200-1000 fc
  • 50-250 fc
  • 10-50 fc

Because display screen luminance typically ranges from 10 to 50 fc, take readings from the bottom scale only.

Adjustments

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

I Adjustments

Light Meter Setup - 4

Date Stamp

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.

Lens

Side Switch

Lens

Side Switch

Model L-248

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.

Red Area

Place the lens against the middle of the screen and press the read button to read the scale.

Model 246

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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