0.4 second response2~3 times sampling per second, instantly to measure out how much luminosity intensity you're getting, no more guessing. Wide measure range this light meter can measure luminance at 0.01~400,000 lumens, (0.01~40,000 foot candles), which is much wider than the others. resolution 0.01. Easy to usethe light sensor can be rotated 270º, so you don't need to turn around the light meter to measure luminosity intensity from different angles. just rotate the sensor, and you can still read the illuminance at front. Memorize the light readingsthis lux meter can help you record 33 sets of readings,temp testing, the relative measuring mode will show you the difference between current / recorded data. ideal lux meter to measure light intensity for led grow lights,garden, plants, school, office, state, led lights, indoor and outdoor. Auto-ranging light meter thanks to the silicon photo diode with filter, the bt-881d lux meter can take accurate lumens reading for led lights, grow lights, sun light forget speculating, know exactly the changing of luminosity power from the distance indoors, outdoors, in the greenhouse, for plants, orchids.