A MASKING TECHNIQUE FOR CONTRAST CONTROL IN ELECTRON MICROGRAPHS

Abstract

An electron micrographic negative that is uneven because of the nature of the specimen, e.g., bone or because of faulty technique, i.e., uneven development, compression marks in the section, etc. can yield even prints when an unsharp positive transparency (mask) is superimposed in register with the negative during the printing. Because of the lack of sharpness in the mask, fine-detail contrast is not affected, but large-area contrast is reduced. The method is essentially a way of "dodging" or "burning in" areas of complicated shape.