The first Summicron for the Leicaflex, introduced in 1964 was a Canadian design, as was the Elmarit-R 1:2.8/90. (the 35mm, the 135mm and he 180mm were of Wetzlar origin). This Summicron could be focused till 50cm, a must for a reflex lens and can be compared to the 1 meter limit with the rangefinder version. This additional focusing range asked for a different type of correction. Curvature of field had to be small at full aperture and focus shift should be contained as well. The higher contrast of this lens, when compared to other lenses, including the competition, was quite noticeable. Research had indicated that film-emulsions could deliver a higher sharpness impression and a higher level of recording of fine detail if the acutance (or micro-contrast) was enhanced. Lenses that could use this characteristic with success had to be of higher contrast than was customary in those days.