Billed as the successor to the Canon S II, this camera was first called the "S IIb." The designation was soon changed to "II B."The hallmark feature was the three-mode optical viewfinder. It had a positive and negative lens element in an optical block which rotated to change the viewfinder magnification. A lever could set one of three magnifications from 0.67x to 1.5x to match the focal length of the interchangeable lens. This feature received very high acclaim.
The lens mount was a universal, threaded flange compatible with Leica. Later in the production, a new diecast body was used to maintain precision and improve mass productivity. Development of the fast Serenar 50mm f/1.9 lens (6 elements in 4 groups, Gauss-type) was also completed and bundled with the II B as the standard lens. Not included with body only.