The invention provides a device for measuring radiation, as well as a method for measuring with the device, and a controllable lighting system with the device. The device (l') has a side wall (2) with a sensor (5, 5'), a radiation entrance opening (4'), and optionally a top wall (9) and bottom cap (10). The sensor is sensitive only to indirect radiation that is reflected at a reflection area, such as a ring (12a - 12b). The device is not sensitive to dust deposition, because most dust is blocked by the side wall (2), while any other dust will pass the sensor surface and reflection area(s) on air currents parallel thereto, without any deposition of dust or dirt. Hence the sensor will give more reliable measurements, even in dusty environments. The method involves orienting the device with respect to the light to be measured and to possible currents. The controllable lighting system involves measuring light levels with the device, and having a control unit control one or more lamps on the basis of those measurements.