Parallax Corrected Bright Frame Viewfinder The parallax corrected bright frame viewfinder of Minox 8x11 camera since 1948 was a revolutionary contribution by Walter Zapp. Leica screwmout rangefinders before fifties had squinty viewfinder with no parallax correction. The first Leica rangefinder camera with bright frame parallax corrected viewfinder was the Leica M3 of 1954 ( so was IIIg of 1957) According to Minox camera authority Hubert Heckmann, Walter Zapp had completed his revolutionary bright frame parallax corrected viewfinder in 1942, and incorporated in post war Minox. If my understanding is correct, that means the Minox II of 1948 had already parallax correction. That means Minox parallax corrected viewfinder predated the first parallax corrected Leica M3 by at least six years. To day, parallax correction is still exclusive to Leica rangefinders and metal Minox 8x11 cameras. Many deluxe compact 35mm camera, such as Contax T2 has only a parallax correction marking.