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lights, negative and image

NEATSFOOT OIL—An oil obtained from the feet of neat cattle.

NEGATIVE.—The term applied to the image of an object or objects, and in which the lights and shades are reversed. A negative is usually made by direct action of the light on the camera. The image shining upon the sensitive dry plate causes parts to become darkened when subsequently treated with the developer. The lightest parts of the image cause the densest deposits, so that it will be seen that the image is darkest in those portions which are the lightest in the image itself. Negatives can also be made by printing from a positive.

Negatives are usually made upon glass by the gelatino-bromide (dry plate) or collodion processes, principally the former. Various other supports for the sensitive film have been used. (See Film Negative Process. Stripping Films. Paper Negatives.) A perfect negative is one in which all the gradations or light and shade are correctly and harmoniously rendered. It should be thin and perfectly clear. In some parts of the deepest shadows the glass should be almost clear, while in certain parts of the high lights the film should be almost perfectly opaque. Between these two extremes there should exist as many gradations

of tone as possible. If only a few semi-tones are present in the negative, positives made from it will be either weak or hard according to the difference in the opacity of the film in the lights and shadows.

The brilliancy of the negative is dependent upon the correctness of the exposure and sub sequent development. If under-exposed, the high lights usually appear black and the shadows perfectly clear without detail, and the gradation of tone between these is, to a great extent, absent. The resulting positives will be hard pictures with masses of black and white without any detail or semi-tones.

If over-exposed, the plate appears too much of the same tint, the shadows appear fogged, the high lights are too light, and the half-tones are almost entirely lost. A positive from such a negative would be too light in the shadows, and too dark in the lights. An over-exposed plate can sometimes be remedied in developing, so that it possesses better printing qualities.