The Extech LT40 LED Light Meter can measure the intensity of light from white LED light sources, and can also measure the intensity of light from fluorescent, metal halide, high-pressure sodium and incandescent sources (for reference only, with unspecified accuracy).
The Extech LT40 is a white LED light meter that measures illuminance in Lux or foot-candles. It features auto-ranging, data hold, max/min/average modes, and zero calibration. The device is designed for indoor use and includes safety instructions for battery replacement and disposal. It measures up to 40,000 fc (400,000 Lux) with cosine correction and a 2.5 Hz display update rate.
The manual covers operation, calibration, battery maintenance, and environmental conditions. It includes a table of typical light levels for various environments and specifies general specifications like sampling rate, display, and operating conditions.
| Units | Lux or Foot-candles |
|---|---|
| Range | Up to 40,000 fc (400,000 Lux) |
| Resolution | 0.4 Lux up to 500 Lux, 1 Lux up to 9999 Lux |
| Display | 4-digit LCD with low battery icon, overload, and function indicators |
| Sampling Rate | 2.5 times per second |
| Battery Type | 2 x 1.5V AAA batteries |
The LT40 can measure up to 40,000 fc (400,000 Lux).
Readings above 9999 use a x10 or x100 multiplier (1 fc = 10.76 Lux).