A system and method utilizing the principles of axial chromatic aberration for auto-focusing an image onto an image sensor are provided. The system and method are particularly suitable for incorporation within an optical code reader. A signal processor analyzes data signals representative of the intensity or magnitude of wavelength components of an impinged image onto the image sensor for determining a value indicative of the focus quality of the impinged image. An actuator controls movement of a lens in accordance with the determination until obtainment of a desired focus quality. A decoder decodes the image having the desired focus quality.