Extech 401020 Lux Meter

This lux meter plugs in to the -ve (COM) and +ve (voltage/diode/etc.) ports on an Extech DMM. It has three ranges, which measure up to 2,000, 20,000, or 50,000 lux.

• <2000 lux:: 0.1mV/lux. 47 lux would output 4.7mV.
• <20,000 lux: 0.1mV/10 lux. 8,455 lux would output 84.55mV.
• <50,000 lux: 0.1mV/100 lux. 24,809 lux would output 24.809mV.

Note that the above lists uses 0.1mV measurements, not 1mV. Set your DMM to its mV range, and multiply the number by ten for the lux meter's first range, by one hundered for its second, and by one thousand for its highest.

This seems like a pretty good unit, and I'm pretty satisfied with its measurements and performance. It's about $60, runs on a 9V battery, and requires a DMM for operation.