The Leica APO-Summicron-M 50mm f/2.0 ASPH Lens represents a true milestone in photographic lens development. You need look no further than the MTF chart to understand what makes this piece of equipment so significant: At an aperture of f/5.6, the lines for both tangential and sagittal structures are absolutely flat--meaning the lens has no image degradation whatsoever. The graphs for f/2.0 and f/2.8 are highly impressive, as well. This is an achievement previously believed by many to be impossible in the field of optics.
Even the finest of details are resolved with greater than 50% contrast across the entirety of the image field. Vignetting is restricted to a mere 2 stops at full aperture in 35mm format, equivalent to about 1 on Leica's M8 models, and stopping down to f/2.8 visibly minimizes this light deterioration towards the image's edges, with virtually none but the natural vignetting remaining. At a maximum of 0.4% (pin cushion), distortion is so low, it's practically imperceptible.
Eight lens elements combine to realize this exceptional performance. Every image you capture with this APO-Summicron-M lens--in any photographic situation--will demonstrate extreme sharpness and resolution throughout, providing you all the validation you need to know that you've made a superior choice. Plus, the lens' apochromatic correction reduces chromatic aberration on sharp edges to deliver the most natural rendition of each detail. The result? You enjoy the best possible reproduction results at any and all print sizes.
To enable such apochromatic correction, which produces a common focusing plane for 3 light wavelengths, 3 of the 8 lens elements are constructed of glass with high anomalous partial color dispersion, while 2 of the remaining 5 feature a high refractive index. In the rear group, the first lens' aspherical surface works to minimize spherical aberration and flatten the image field. Optical construction is Gaussian type, while the arrangement of lens elements resembles that of the Summilux-M 1:1.4/35 mm ASPH. This group, located behind the diaphragm, comprises the floating element that moves independently of the others in focusing, altering position relative to the front group, to ensure that the lens delivers incredible image quality throughout its focus range--even at the closer focusing distances.
To realize the stunning apochromatic correction, it was necessary to utilize specially-formulated glasses based upon original creations of the former Leitz glass lab. Leica understands that the process of working with these glasses is truly a fine art, which is why they have been integrated so expertly into this Summicron lens.
The lens' design is based on that of its predecessor, with the 50mm focal length and maximum f/2.0 aperture serving as the foundation for the rest of the development. With a compact body only slightly longer and heavier than the Summicron-M 1:2/50mm, and with an almost identical diameter, this lens delivers noticeably superior image quality. In the 30 years since the launch of the 1:2/50mm, Leica has accomplished a lot--but this is certainly one of their crowning achievements.
This groundbreaking lens is the culmination of 150 years of hard work. The APO-Summicron-M 50mm owes its unparalleled performance to the perfect interaction of all design and construction elements--from optical calculation to selection of materials to highly sophisticated and elaborate manufacturing and finishing.
Constructed completely by hand in Germany, and composed of only the best materials, the APO-Summicron-M 50mm f/2.0 ASPH Lens is a testament to the amazing achievements that are possible when advanced technology, vast knowledge, and meticulous, expert craftsmanship collide.