The Leica Summarit-S 35mm f/2.5 ASPH CS Lens is a classical wide angle lens with high optical performance. Two aspherical lenses together with special highly refractive glass with atypical partial dispersion, yields excellent sharpness and contrast throughout the image field. This reference-class lens displays consistently high image performance utilizing an inner focusing system with a floating element. The Summarit-S 35mm f/2.5 ASPH CS is equipped with an integrated Central (leaf) Shutter. Photographers can activate the shutter via the camera's main switch. It enables flash units to be used at a shutter speed of 1/500 second, and it performs effectively with studio flash units. The shutter also has an electronically-controlled drive guaranteeing reliable, fast exposure times and low energy consumption. This lens displays maximum performance across the entire image field at all apertures. With a broad effective range of focus (minimum distance of 21.65' (55cm), it is possible to produce unusual and attractive compositions. With Leica's high-degree of lens precision there is almost no discernable vignetting, distortion and chromatic aberrations. Thus, images don't require a large amount of post-production corrections. The Summarit-S 35mm f/2.5 ASPH CS is equipped with a Leica-designed microprocessor for precise autofocus and iris diaphragm control with silent gearing and it has a focus ring with enough drag to let the user to override the autofocus at any time.