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As a moderate wide-angle prime, the APO-Summicron-SL 35 f/2 ASPH. is almost a universal lens. Its fast autofocus, robust design and construction and exceptional imaging quality make it an outstanding lens for reportage and a convincing choice for other areas of photography such as architecture, landscapes, portraiture and studio work. It is perfectly matched to the cutting-edge SL-System and has been conceived for a long working life under professional shooting conditions.

Innovative production methods and new technologies paired with exceptional imaging performance make the latest lens of the Summicron-SL series the new reference among reportage focal lengths. Thanks to the L-Mount standard used for this lens, the APO-Summicron-SL 35 mm f/2 ASPH. is also fully compatible with cameras manufactured by other partners of the L-Mount Alliance with the lens mount developed by Leica.

This Summicron-SL lens delivers extremely high imaging performance at its largest aperture and is ideal for photography in difficult lighting conditions. In its construction, a total of 13 extremely complex lenses ensure the very highest levels of the image quality attributes so typical for Leica: natural skin tones, soft transitions into the bokeh, outstanding contrast in details and consistent sharpness from corner to corner and edge to edge of the distortion-free image. The following holds true for SL-Lenses in general: the maximum aperture is a usable aperture – stopping down is exclusively a creative imaging tool, and is not necessary for achieving better imaging performance.

All glass elements in an optical imaging system – such as 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 APO-Summicron-SL 35 mm f/2 ASPH., these chromatic aberrations are minimised by apochromatic correction. For this, the majority of the thirteen lens element used in the construction of the lens – five of which have aspherical surfaces – 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.

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 a 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 autofocus drive of all Summicron-SL lenses employs extremely powerful and robust focus stepping motors with DSD^® (Dual Syncro Drive^™). Thanks to these, the entire focusing throw can be travelled completely in only around 250 milliseconds. Leica shows its innovative powers not only in the case of autofocus technology, but also when it comes to manual focusing: Summicron-SL lenses feature a totally new concept for manual focusing in which a ring magnet with alternating north-south magnetization is embedded in the 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.