Abstract: According to a process for regulating the amount of copying light in a closed control loop of a photographic color photocopier equipped with color filters, the copying light influenced by the color filters is selectively measured in the primary colors, red, green and blue. A deviation resulting from the comparison of the real values with predeterminable set values is subdivided into a color deviation and a brightness deviation. The color deviation is compensated by regulating the color filters, whereas the brightness deviation is converted into a correction factor for the lighting time, so that for each primary color the product of the light intensity real value by the effective lighting time is constant and identical to the product of the light intensity set value by the lighting time set value.

Abstract: A measuring instrument for the point-by-point measuring of color originals to be copied for the determination of exposure data, in which the original is illuminated by a condenser light source by way of a Fresnel lens and by means of an objective is imaged over the whole surface on a measuring plane in which a photodiode line can be moved in a straight line over the measuring surface. The movement of the photodiode line over the original image takes place step-by-step by means of a step motor, light measuring signals being created in the individual diodes which each can be assigned to a certain measuring point on the original. The sensing takes place sequentially for the basic colors red, green and blue, in which case one color filter respectively of the corresponding color is introduced into the path of the measuring rays. From the large number of measuring values, the exposure data are computed according to a predetermined algorithm.

Abstract: A diaphragm adjusting arrangement in an enlarging appartus having several lenses with an adjustable diaphragm includes a motor drive for the common adjustment of the diaphragms of all lenses and a device for detecting the adjusting path. By means of the comparison of the actual position of the diaphragms with a given desired position in a control circuit, a control signal is generated for the motor drive to move the diaphragms into the given position.

Abstract: A continuous processing machine for photographic material, particularly sheet-shaped photographic paper, has an input unit for the sheet material to be treated and a variable number of treatment units of the same structure which can be fitted together with one another to form a modular system. Each treatment unit is equipped with a set of conveying rollers and with a synchronous motor used as the drive and includes a toothed gear transmission, the ratio of which can be adjusted corresponding to given values of the advancing speed of the sheet material. A conveyor worm in the bath receptacle of each treatment unit driven by the same motor provides an effective circulation of the bath.The modular structure makes it possible to fit together a variable number of treatment units which are similar with respect to one another to form an equipment unit which, depending on the configuration stage is suitable for different treatment processes.

Abstract: A method for determining the exposure time in photographic copying includes measuring the light intensity at different measuring points of the projected picture of the original to be copied for an initial copying light intensity, and forming a mean value of the light intensity values measured at such points; the exposure time for a current copying light intensity is determined by modifying the aforementioned mean value with a proportional action factor corresponding to the ratio of the light intensity value measured at a selected one of the measuring points for the current copying light intensity relative to the light intensity value measured at the same point for the initial copying light intensity.

Abstract: This invention relates to a process and a device for adjusting a photographic color enlarging or copying apparatus. By means of the measuring device that uses copying light of the enlarging apparatus to be adjusted as the measuring light, the color densities of a test copy made of a test original and of a reference copy which represents a satisfactory picture reproduction of the test original are measured selectively in the colors red, green and blue and are compared with one another. Corresponding to an existing deviation, adjusting control means at the enlarging apparatus that color-selectively influence the amount of copying light are readjusted until the deviation is balanced, and another test copy is made with the new exposure conditions and is measured.

Abstract: This invention relates to a photographic color enlarging apparatus having a measuring device for determining the density of a test copy which, by means of the enlarging apparatus, is exposed from a reference original selected for the test-adjusting of the apparatus. Light-guiding means (15) guide light from the copying-light source of the enlarging apparatus into a measuring level outside the path of the copying rays which receives the test copies to be measured, and a photoelectric measuring sensor (25) receives measuring light reflected by the test copy. As a function of an existing density difference between the test copy and a reference copy, corrections of the exposure values are determined in such a way that a copy exposed under the new exposure conditions has the density values of the reference copy.

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.