Description: The TSL2561 SparkFun Luminosity Sensor Breakout is a sophisticated light sensor which has a flat response across most of the visible spectrum. Unlike simpler sensors, the TSL2561 measures both infrared and visible light to better approximate the response of the human eye. And because the TSL2561 is an integrating sensor (it soaks up light for a predetermined amount of time), it is capable of measuring both small and large amounts of light by changing the integration time.
The TSL2561 is capable of direct I2C communication and is able to conduct specific light ranges from 0.1 - 40k+ Lux easily. Additionally, the TSL12561 contains two integrating analog-to-digital converters (ADC) that integrate currents from two photodiodes, simultaneously. Each breakout requires a supply voltage of 3V and a low supply current max of 0.6mA.
Based on 1 ratings:
It is a very simple device and the library is well written. Needs very little tweaking. I use it to detect quite a low brightness change with high temporal resolution. My first one only started failing after a year of use and abuse (no case and occasional finger prints on the sensors). The second one had a lesser sensitivity and I had to go from 1ms integration time to 2ms to be able to distinguish the two brightness levels in a reliable manner. Overall very satisfied with it but if you use it, try to find a way to encase it in something and it will live much longer and will have better performance.