Its high speed and the unique aesthetics of its field of focus make this telephoto lens the first choice for portrait photographers. At the decisive moment, its almost silent and simultaneously precise autofocus gives photographers more time to concentrate fully on the creative aspects of their subject, the person in front of their camera. Like all Leica SL-Lenses, the APO-Summicron-SL 1:2/90 ASPH. is perfectly matched to the modern SL-System and is constructed for a long working life under professional shooting conditions.
AF System with Dual Syncro Drive™,from zero to sharp in no time. The AF system of the Summicron-SL lens is fast, precise, and almost silent. It thanks its outstanding AF performance figures to the autofocus drive unit. These are limited only by the mass of the lens elements moved when focusing, the travel from infinity to the closest focusing distance and, of course, the amount of space available. In order to preserve the compact dimensions of the lenses, the integration of these components must follow an integral approach. Specialists from the areas of optical and mechanical engineering and electronics worked together in an interdisciplinary team on the development of a unique lens concept based on double internal focusing. This system, comprising two particularly light focusing lenses, allows the construction of particularly small and compact drive systems. In addition to space limitations, the choice of the drive motors is also determined by the AF principle used for focusing.
Higher Contrast for greater perceived depth. With an initial aperture of f/2, this SL-Summicron lens is significantly more compact than faster lenses, but still allows photographers to work with similar depth of field. The reason for this is contrast: the zone of highest contrast is perceived by viewers as being sharp, while zones with lower contrast are regarded as being unsharp. In the case of the SL-Summicron lens, this difference in contrast is considerably higher than that of conventional lenses: sharply focused objects show much higher contrast than objects that are out of focus. This means that objects “snap” more distinctly out of the foreground or background and more effectively isolate the subject. This creates a three-dimensional visual effect with very impressive apparent depth.
In the construction of the Summicron-SL lens, particular attention has been paid to the prevention of stray light and reflections. The optimization of the optical and mechanical design was carried out in elaborate simulations before the construction of the first prototype lens. Unavoidable reflections are reduced to the best possible level by high-quality coating of lens surfaces. The three most obvious functions of a Summicron-SL lens to users: focusing, MF ring, and aperture setting, are all based on a multitude of control systems and mathematical operations. The demands on the electronics are particularly high in the case of the double focusing system. Here, the two autonomous focusing units must be moved in perfect synchronization and positioning data have to be analyzed at a very high sampling rate and passed on to the camera.
The consistently compact dimensions, low weight, and the excellent grip and feel of the SL-Summicron lens is particularly impressive when shooting. Thanks to the almost identical design of the Summicron-SL lenses, feeling for the MF ring is unnecessary after switching lenses and the center of gravity remains largely the same. This means that the camera always lies perfectly in the hand and makes working from a tripod much easier.