Disclosed is a controllable light angle selecting device that includes a fixed light selecting means for transmitting light within a limited acceptance angle, optically connected to at least one light redirecting means capable of achieving a variable angular difference between light entering said light redirecting means and light exiting said light redirecting means. Also disclosed is a photometer employing such controllable light angle selecting device and arranged in the path of light between a light source and at least one light measuring sensor arranged to receive at least part of the light exiting from the controllable light angle selecting device.