This fast, wide-angle lens is available with or without a central shutter and operates practically without distortion. It is therefore ideal for use indoors or for architectural photos. The SUMMARIT-S 1:2.5/35 mm ASPH. (CS) uses two aspherical lens surfaces and special glass with anomalous partial dispersion or high refraction as well as rear-group focusing for the highest performance over the entire focusing range.Central Shutter - the central shutter employs powerful springs as energy accumulators and through its patent pending, innovative design, can attain shutter times of up to 1/500 of a second that are also fully synchronized for flash.Leica S LensesIf you want perfect pictures, you need perfect lenses. What distinguishes Leica lenses from others is the designer's expertise acquired over decades, selecting the highest-quality glass and precision manufacturing with extremely fine tolerances. For the first time in a camera larger than 35mm format, aspherical lens surfaces are being employed along the entire range of lenses for the highest possible imaging performance. High contrast and the finest delineation of details to the outermost corners of the image are the fruit of these endeavors. Pictures that are already optically perfect at the time they are taken do not need corrective post-processing. The image sharpness and the balanced design yield an especially pleasant progression into out of focus areas, serving the creative composition of the picture. All S lenses stand out in attaining their maximum optical performance at full aperture, and are optimized for all other working distances including the close focus range. Leica S lenses require no compromises in their application: from close-ups in the studio to outdoor landscapes set at infinity, the picture quality remains optimal down to the outermost corners even at full aperture. Stopping down only serves to increase the depth of field.All S lenses come with large, effective lens hoods that mount to the accessory bayonet for space-saving storage during transport. The most important focal lengths in the S systems are optionally available with or without the new Leica central shutter.