||Digital photography is based on the conversion of light by sensitive matrix (array of electronic photodetectors) to capture the image which is then digitized and stored as a computer file for further processing and printing. The spectral sensitivity of the cameras is in good agreement with the spectrum of action of the photosensitive hormone melatonin. Digital photography can be used to quantify light pollution acting on the physiology of living organisms. The chapter discusses the principles of spectrophotometry. A portable spectrophotometer for the measurement of light pollution is proposed by Cinzano. It consists of a cooled CCDcamera and a small spectrographic head which is equipped with a De Amici prism composed of two external crown prisms and an inner Flint prism. Sky quality meter (SQM) is a portable photometer for measuring sky brightness and for light pollution monitoring. This device collects the light from a wide solid angle.