Voigtlander Black M 90mm f2.0 APO ULTRON offers very high optical performance in a small compact lens. The apochromatic design reduces axial chromatic aberration close to zero. Small for its focal length and aperture, the M 90mm F2.0 APO ULTRON does not protrude into the frameline. The 12 blade aperture diaphragm produces an aperture opening as circular as possible. Out-of-focus areas of images are drawn naturally and point light sources are drawn as soft round bokeh rather than as polygonal shapes. Compact High Performance apochromatic optical design makes the on-axis chromatic aberration of RGB, as close to zero as possible. The optical system uses abnormal partial dispersion glass for 6 out of 8 elements in 7 groups. The reversible lens hood is included. Rangefinder close focus is .9 meter. Fstop range is F2.0 to F16. Weight is 12 ounces. Length is 2.49 inches. Diameter is 2.43 inches. Filter size is 52mm. The lens extends only 2.49 inches from the lens mount.