The Leica Correction Lens is the best solution to match the difference between the focus of the eye and camera. Although the combined viewfinder/rangefinder of the Leica M helps with precise focus, the Diopter Correction Lens is the best solution.The Leica Diopter Correction Lens are exclusively designed for M-series camerasThe Leica Correction Lens is a good solution for photographers with minor sight deficienciesThe use of Diopter Correction Lens makes it easy to compose images on the viewfinder than with eyeglassesThese correction lenses are available in grades of plus/minus 0.5, 1, 1.5, 2 and 3 diopters