. Every lens tested over one hundred times . In this way, Zeiss achieves 100% quality assurance, with every lens being tested exactly for more than 100 different criteria during its production. Carl Zeiss does not rely on statistical process control and/or spot inspection, like it has become the cost saving standard in mass producing industries. Zeiss rather performs a 100% quality control, like it is done for airplane components and other very demanding industrial products. . . In addition, some decades ago Carl Zeiss was the first lens manufacturer to publish MTF performance diagrams for its lenses. Several manufacturers have, in recent years, followed this example – but with one decisive difference. The curve diagrams of Carl Zeiss show not just optimistic computer simulations, but the properties of lenses which have actually been built. They are not merely computer-generated curves which give no indication whatsoever of how good and uniformly the supplier manufactures this lens in volume production. .