The Leica APO-Macro-Summarit-S 120mm f/2.5 (CS) is a true dual-purpose lens: firstly, it is a macro lens for close-up photography up to a reproduction ratio of 1:2. Secondly, it is a fast telelens with an exceptionally large maximum aperture of 1:2.5. It achieves exceptional imaging performance at all apertures and distances. Hence, dimming only increases the depth of field but doesn't improve the contrast rendition, opening fascinating possibilities for image compositions with selective sharpness.
The design comprises nine elements in seven groups. Front-group focusing and a floating element provide superior contrast rendition up to an extremely close range. including three elements with anomalous partial dispersion - two of which are highest-quality fluoride lenses for the correction of chromatic aberration. The outstanding contrast in even the finest structures.