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The centerfilter provides reduction of unavoidable natural light loss caused by physical laws and determined by the angle of view must be exactly correlated in its effective diameter and in the density gradient with the wide-angle lens. Not only the angle of view is decisive, which for several Super-Angulons or various Super-Symmars can be the same, but also the position of the filter relative to the nodal point of the object-side which is determined by the barrel of the lens. For optimum effect, it is therefore not sufficient simply to use a centerfilter of the proper thread diameter.
