Leica APO-Summicron-SL 50 mm f/2 ASPH.

Twelve extremely complex lens elements – three of which have aspherical surfaces – arranged in ten groups contribute to the ultimate in terms of image quality, even wide open. After all, Leica lenses fulfil the following promise: the maximum aperture is a working aperture. In view of this, stopping down is exclusively a creative imaging tool, and is not necessary for achieving better imaging performance. Natural skin tones, soft transitions into the bokeh, outstanding contrast in details and consistent sharpness from edge to edge of distortion-free images are further quality characteristics of lenses manufactured by Leica Camera, and also apply to the APO-Summicron-SL 50 mm f/2 ASPH.

All glass elements in an optical imaging system – for example lenses – refract light in certain colours to a different extent. This leads to the effect that not all rays of light from a multi-coloured subject are focused at a single imaging point – the result of this is chromatic aberration. In the new APO-Summicron-SL 50 mm f/2 ASPH. these chromatic aberrations are minimised by apochromatic correction. For this, the majority of the lens elements used in the construction of the lens are made from specially formulated, high-quality glass types with anomalous partial dispersion that push even the innovative manufacturing methods of the Leica Factory to the limits of the technically possible.

The autofocus drive of all Summicron-SL lenses employs extremely powerful and robust stepping motors with DSD^® (Dual Syncro Drive™). Thanks to these, the entire focusing throw can be travelled completely in only around 250 milliseconds. Leica Camera also takes an innovative approach in the case of manual focusing technology: Summicron-SL lenses feature a totally new manual focusing ring construction concept. In this concept, a ring magnet with alternating north-south polarisation is embedded in the manual focusing ring. The magnetic field changes its polarity when the ring is turned. A sensor monitors the status of the magnetic field and sends the data to the main processor. The drive then shifts the lens to the corresponding focusing position on the basis of the angle of rotation and the rotational speed – this in turn enables even faster and more precise manual focusing.

Both the construction and the design of the cutting-edge Summicron-SL line represent the next step forward in the development of lenses for the Leica SL-System. New, extremely precise manufacturing methods and measuring technologies have been developed especially for the production of these lenses. The results of this are reflected not only in the more compact dimensions and considerably lower weight of the lenses, but also in their excellent imaging performance. In the construction of the APO-Summicron-SL lenses, particular attention has been paid to the prevention of stray light and reflections. Together with an optimisation of the optical and mechanical design, the application of high-quality coating to lens surfaces reduces unavoidable reflections to an absolute minimum. Thanks to effective sealing against dust, moisture and water spray, and Aquadura coating of the exposed lens surfaces, the lenses can be used without a second thought in almost any weather conditions.

The APO-Summicron-SL 50 mm f/2 ASPH. is on sale now.