ABSTRACT
We all tend to take a modern lens for granted. It is just accepted as an image-formingcollection of glass elements, somewhat overpriced and easily damaged. In fact, everygood lens is really a skilfully solved set of problems concerning the control of light. Designing a lens means juggling image quality, the picture area covered, consistency over a wide
range of subject distances, an acceptably wide aperture – and finally coming up with something
which is not too large, heavy or expensive to manufacture.