The Dictionary Of Photography

A True Historic Record Of The Art & Practice Of Photography 100 Years Ago.

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Reversal                                           Reversed Negatives
Reversal is when those parts of the image which should appear dark in the negative come up light, and vice versa. It is due to the extreme action of light, and is also known as solarisation. There is no remedy when reversal has taken place. (See Reversed Negatives (3rd method, p. 563).
Reversed Negatives. This means that the position of the picture is reversed as regards right and left. Reversed negatives are required for certain photo-mechanical work. They may be made : - First, in the camera direct; secondly, by reversing the negative film itself; thirdly, by reproduction from other negatives. First method : Taken in the camera direct. This again may be divided into three heads - viz., (a) those taken by means of a silvered reflector; (b) those taken by means of a prism ; and (c) those taken through the glass plate on the back of the film. By
Fig. 112.
the first of these methods a piece of glass silvered on the external surface must be used, and mounted in the following manner: - c, camera ; l, lens; f a b d is the section of a hood which can be screwed on to a camera; a d, the reversing mirror, placed at an angle of 450 with the axis of the lens, and so adiusted that the axis of the lens is continued to the centre of the mirror ; e is a small door, which can be opened or closed at will (in fig. 112, a d is not shown at the specified angle). The camera is placed sideways towards the object, which is reflected from the exterior surface of A d to the lens. By the second method a right-angled prism (see Prism Reversing) is used, as shown in fig. 113. The principle involved being precisely the same as with the mirror, the camera is again turned sideways to object, a b is a hood to fit on lens to take the place of the cap. c c is a right-angled prism, whose breadth is greater than the diameter of the
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