ISO 9039:2008 specifies methods of determining distortion in optical systems for the purposes of quality evaluation. It applies to optical imaging systems in the optical spectral range from 100 nm to 15 000 nm which, by their design, aim at a rotationally symmetric image geometry. It is applicable to electro-optical imaging systems provided that adequate rotational symmetry of the image is guaranteed. It does not, therefore, apply to anamorphic and fibre optic systems.