M50mm F1.1lens optics contains 7 elements in 6 groups and is based on Sonnar formula. It includes two high refraction optical elements of index 1.9 to improve picture quality and lens portability. R&D process involved analysis of field curvature and image astigmatism influence on image and out of focus areas.Numerous corrections and improvements made to receive great image performance.Using lens wide open at F1.1 aperture delivers pleasant bokeh. Stopped to F1.4 it improves sharpness while keeping smooth out-of-focus areas. Repetitive corrections of spherical and chromatic aberration lead to very well controlled light spots shape, and good contrast and sharpness in focus area of this large aperture lens .