A simple spectrophotometer was designed using cardboard, a DVD, a pocket digital camera, a tripod and a computer. The DVD was used as a diffraction grating and the camera as a light sensor. The spectrophotometer was calibrated using a reference light prior to use. The spectrophotometer was capable of measuring optical wavelengths with a theoretical accuracy as high as 0.2 nm. Using this spectrophotometer, wavelengths are determined via image processing. (Contains 13 figures and 1 table.)