A ring light illuminator with annularly arranged light sources is disclosed. To each light source there corresponds a light collector, a homogenizing means for light from the light source, and an anamorphic system for imaging an output of the homogenizing means into an area to be illuminated. The anamorphic system compensates deformations of a cross-sectional area of a light beam in a surface to be illuminated due to an oblique angle of incidence of the light beam onto the surface. The homogenizing means in embodiments is a rod, into which light from the light collector is directed. The end of the rod opposite the light collector is imaged by the anamorphic system into the area to be illuminated on the surface. Also disclosed is a method for illumination.