One foot-candle (Fc) indicates the illuminance from a surface of one
square foot, all points of which are one foot from a uniform source of
one candela.
Unit conversion for illuminance scales
1 Fc = 10.764 Lux
1 Lux = 0.09290 Fc
Conversion formula for illuminance and light intensity
E = I / r
2
E --- illumination value (Unit: Lux)；
I --- Light intensity of the light source（Unit: cd）；
r --- Distance from the luminous surface of light source to the optical
detector (Unit: m）.
During the measurement, the minimum distance between the luminous
surface of light source and the opto-sensor should be more than 15
times greater than maximum size of the luminous surface (or
opto-sensor).
Typical practice cases
Remove the protection cover of the MT-4617LED multi-functional light
meter sensor and place it at right angle to the light source.
Press and hold the MT-4617LED power key ④ for a short time to
power on the light meter. The LCD screen will illuminate（about 5
seconds）with the buzzer beeping twice, and “AUTO” will appear on the
middle of LCD display. This indicates that the auto measurement mode
is ON.
Press and hold the manual range switching key ⑨ of the MT-4617LED
for a short time, “MANU” will appear on the top left position of the LCD
display, indicating that the manual range switching mode has been
activated. In this mode, each time press and hold the key for a short
time, the meter will switch to 20.00Lux—> 200.0Lux—> 2000Lux—>
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