Abstract: A measuring device for selecting the color composition of the copying light when copying a film frame original in a photographic enlarging or copying apparatus has two groups of red-, green- and blue-sensitized measuring cells of which one group receives measuring light entering into the film frame original and the other group receives measuring light coming out of the film frame original. The measuring signals of each color from both groups of measuring cells are combined with one another and from the combination signals, ratios are formed of the color parts with respect to one another. As a result of the combination of measuring signals of the copying light before and after the flow through the film frame original to be copied, an undercompensation of the color deviation of individual originals with respect to a reference original is achieved.