GB592034A - Combined photographic printing and viewing arrangement - Google Patents

Abstract

592,034. Photographic contact and projection-printing apparatus. URBACH, F. April 26, 1944, No. 7757. [Classes 98 (i) and 98 (ii)] Apparatus is described for making prints by contact or projection upon sensitive material yielding a visible image directly, and for viewing them during printing by illuminating them with light to which the sensitive material is insensitive and observing them through means receiving this light only. Ordinary print-out material may be used. The viewing of the image may take place with the printing light screened from the print by a movable element, or with the printing light temporarily switched off; or it may take place while printing is actually going on if a filter absorbing light from the printing source is interposed between the print and the viewing means. Fig. 1 shows a projection-printing box in which light from the printing source 1 passes through a blue filter 9 and condenser 2 to a negative 3, and is projected therefrom by a lens 4 on to the print-out material 5. The viewing means comprises a source 6 of light, e.g. red, to which the material 5 is insensitive and a viewing telescope 8, fitted with a red filter 10, receiving light from the print via the lens 4 and an opaque mirror 7 pivoted at 11 so that it may be swung up into the dotted inoperative position for printing and let down for viewing, in which latter position it screens off the printing light from the print. Instead of an opaque mirror 7, a semi-transparent mirror fixed in the inclined viewing position may be used, so that printing and viewing may occur simultaneously ; or for the same purpose the inclined mirror may be circular with alternate apertured and opaque sectors and may be continuously rotated. In a further modification, wherein prints are to be made on transparent or translucent sensitive material, the mirror 7 is dispensed with, the print being illuminated on its front face by the viewing light source, and its rear face being viewed, without interrupting the printing, through a lens fitted with a red filter. Fig. 3 shows a contact printing box in which printing light from a source 14 passes through a condenser 15 to a negative film 12 in contact with a crossed print-out film or paper 13 fed between spools 16 on a frame pivoted at 17 so that, when the film is to be viewed, the film may be turned down into the dotted position out of the path of the printing light, where it is illuminated by a source 19 of viewing light fitted with a red filter 20, and viewed through a lens 18. In a modification using transparent or translucent print-out material, the negative and positive films remain in contact, a blue filter is located between the condenser and negative film, the print is illuminated on the rear face by the viewing light source, and this face is viewed, without interrupting the printing, through a lens fitted with a red filter. It is stated that if the print exhibits colour, the contrast of the observed print may be varied by using different colour filters in the viewing device.