The Zeiss Ikon Model 563/24 was a complete redesign of the previous II/III cameras, and was sold by Zeiss Ikon from 1950 to 1961. Gone were the troublesome silk shutter straps; in their place were straps made of nylon; a flash synch was added; and the body's size and weight were reduced. Shutters were still guaranteed for 400,000 cycles. The same internal/external bayonet mount was kept. This line was an engineering and manufacturing tour de force, and is considered by many to be the finest camera ever made. As with the II and III, the IIa was the base camera, and the IIIa had an added exposure meter attached on top of the camera. The shutter lammels were changed to duraluminium, lighter and faster to start and stop; however, they were thicker, too. The old Biogon did not fit, so a new one was designed together with the new Biogon 21 mm f 4, gave new perspectives to wide angle photographing.