DIN ISO 11421:2010-10

The optical transfer function (OTF) is one of the main criteria used for objectively evaluating the image-forming capability of optical, electro-optical and other photographic systems. The International Standard lists the main sources of inaccuracy in OTF measuring equipment and provides guidance on how these can be assessed and how the results of these assessments can be used in estimating the error band in any measurement of OTF. One of the aims in preparing this International Standard is to encourage the setting of more realistic uncertainty levels for the results of OTF measurements. Another is to encourage the use of methods of expressing the accuracy of OTF test equipment which recognize the fact that the accuracy of a particular measurement is a function of both the equipment and the test piece. This International Standard gives guidance on evaluating the sources of error in optical transfer function (OTF) equipment and in using this information to estimate errors. It also gives guidance on assessing and specifying an accuracy value for a specific measurement value and recommends methods for routing assessment. The main body of this International Standard deals exclusively with the modulation transfer function as part of the OTF. The phase transfer function (PTF) is dealt with relatively briefly in Annex A. The International Standard has been prepared by ISO/TC 172/SC 1, in collaboration with German experts. At DIN, the German Institute for Standardization e. V., Working Committee NA 027-01-02 AA "Grundnormen der Optik" ("Fundamental standards for optics") of the Optics and Precision Mechanics Standards Committee (NAFuO) is responsible for the preparation of this standard.