Apple Macintosh Performa 577 - Manual (Page 146)

Adjustments Light Meter Setup - 25
Model L-248
1 Press the red button on
the back of the light
meter. If the reading is
out of the red area,
replace the battery.
2 Move the side switch to
its upper position so that
the scale reads 10
through 18.
3 Uncover the lens of the
meter.
4 Place the lens against the
middle of the screen and
press the read button to
read the scale.
Read Button
Lens
Side Switch
Scale
Red Area