Amprobe (Meterman) LM631A Digital Light Meter

© Brooke Clarke 2010

This is the light meter that's most commonly used on Candle Power Forums to measure the light output of flashlights.  I think there are two reasons for this, one the meter seems to have reasonable calibration and two, it has a 2.5 mm socket with a mv analog signal output that can be connected to an external meter or data logger.

This is not an auto ranging instrument, if you get "OL" you must manually press the RANGE button.   Each press upranges the meter and when on the highest range cycles back to the lowest range.
20.00, 200.0 & 2000 lux
20.00, 200.0, 2000 & 20000 fc

There are four AAA batteries in the long handle.  But for long flashlight light vs. run time tests it would be nice to have an easy way to use external power.  That might be donw by replacing the 2.2 mm external analog output jack with a stereo version.

Optics
Weston 594 Photronic Light Sensor