"COMPENSATOR " NEGATIVES A system advocated by Newton Gibson and published in April, 19o5, for preventing hala tion without backing and controlling contrasts when taking difficult subjects, particularly interiors. The method is to place a dry plate, glass side towards the lens, in the camera and to give a very short exposure in order to secure the high-lights and not the shadows ; the plate is then developed, fixed, and dried. When quite dry the under-exposed negative is placed in the dark-slide in contact (film to film) with another dry plate, and the same view taken again through the compensator negative, taking care to give a full exposure for the shadows. If the first negative is of the right density, the second will develop in good gradation, the win dows and other high-lights not being over exposed and too dense, because of their being covered by the compensator through which the light has to pass to act on the second plate. Obviously the camera must not be moved in the slightest degree between the two exposures, or the picture will not be in register ; and the system is therefore out of the question where the camera cannot be left untouched for some time.
Success depends mainly upon the accuracy of register, and the relative amount of exposure and development necessary for the compensator negative and for the final negative. It is possible to over-correct the highest lights by making them so dense on the first negative that light will not go through them.
The process can be adapted to existing faulty negatives. A thin positive is made by contact an celluloid film, and when developed and dry it is bound or cemented to the negative in the position occupied when printing. The thick ness of the celluloid film between the negative image and the sensitive paper when printing will cause no trouble if a fairly concentrated light, entirely from the front and not from the sides of the frame, is used for printing.