The APO-Sironar-S, a universal lens with 6 elements in 4 groups, is constructed with ED(extra-low dispersion) glass, which has been modified to provide the highest image reproduction quality. Like the APO-Sironar-N, its applications are practically limitless. The angle of view has been increased to 75° to permit more shift.
Today's modern fully-multicoated lenses for large format available from the 'big four' are all so good that for the most part they are practically interchangeable. There are exceptions here and there, however, such as newer assymetrical lens designs providing more coverage with a smaller size and weight. But in the tried and true 6-element, 4-group standard lens formula, the Sironar-S stands head & shoulders above the rest thanks to its ED glass. Beyond the increased coverage, this lens can be used with exceptional sharpness even at apertures which are far from ideal in the world of large format. While you might be bitterly disappointed with a skillfully-crafted effort at f/11.0 with another "normal" 6-element/4-group lens, the Sironar-S will still impress.