This document is the Extech LT40 LED Light Meter User Manual, which introduces the use and precautions of the light meter.
The Extech LT40 is a light meter designed primarily to measure light intensity from white LED light sources, though it can also measure light from fluorescent, metal halide, high-pressure sodium, and incandescent sources for reference only. The instrument measures illuminance in Lux or foot-candles (Fc) and features a 4-digit LCD display with auto-range functionality. It is capable of measuring light up to 40,000 Fc (400,000 Lux) and includes features such as data hold, maximum/average/minimum memory, and zero calibration adjustment.
| Units | Lux, Foot candles |
|---|---|
| Max Measurement (White LED) | 400,000 Lux |
| Max Measurement (Foot Candles) | 40,000 Fc |
| Accuracy (White LED) | ±(3%reading + 3 Lux) |
| Display | 4-digit LCD |
| Photo Detector | Silicon photo-diode with cosine correction |
| Power Supply | 2 x 1.5V AAA batteries |
| Battery Life | Approximately 200 hours |
| Operating Temperature | 5 to 40°C |
| Dimensions | 133 x 48 x 23 mm |
The LT40 measures white LED light sources and can also measure fluorescent, metal halide, high-pressure sodium, and incandescent sources for reference only.
Press the LUX/FC button to toggle between Lux and FC (foot-candles) measurement units.
The meter can measure light up to 40,000 Fc (400,000 Lux).
The battery life is approximately 200 hours.