This section is from the book "Complete Self-Instructing Library Of Practical Photography", by J. B. Schriever. Also available from Amazon: Complete Self-Instructing Library Of Practical Photography.
(See Mirror, Silvering.)
(See Lens, Single.)
A viscous solution made by boiling shreds of leather, parchment, etc., in water and then purifying it. Also from common glue, scraps of hides, horns, hoofs, etc. It is used in the manufacture of paper.
A landscape scene which lacks sky values, or rather cloud effects, is not a perfect landscape. Owing to the fact that the sky is extremely actinic it is many times over-exposed before sufficient exposure has been given to the foreground or landscape proper. For this reason all detail in the clouds is lost. There are various methods employed for securing proper cloud effects in landscape scenes. Some shutters are so regulated that the sky portion will receive must less exposure than the foreground. Ray filters, which lessen the action of the blue rays of light, are also employed for this purpose, but judgment must be exercised in their use or an unnatural appearance will be given the picture, the cloud effect being too strong if too dark a filter is employed. The usual method is to make cloud negatives and print them in the picture after the foreground from another negative has been printed. All of these methods are given careful consideration in the text.
A large light generally constructed specially for studio illumination. There are three general forms of skylights, known as double-slant, single-slant and perpendicular lights. Various photographers give preference to one style or another, according to their own individual ideas. The main idea is to have a light that will facilitate the photographer in perfectly lighting his model. A soft light is required; therefore, ground-glass or ribbed glass is to be preferred to plain glass. The skylight should be perfectly rain proof and have adjustable curtains which will enable the operator to secure the proper angle of light and the amount of illumination desired. Diffusing curtains are also of value in softening the light, although movable screens and diffusing devices are employed by many photographers for locally controlling the light effect on the model. When a studio room is of sufficient length the skylight should be located in the middle of the side wall, so as to permit of one working from either end of the skylight. In smaller rooms the skylight should be in the side wall, at least five feet from one end of the room.
Negatives on which exposures have been made of various cloud forms, to be used in combination printing with landscape negatives.
A hood or similar arrangement placed on the lens to prevent too strong illumination from the sky to strike directly into the lens. Some forms of sky shades are constructed to allow of a shorter exposure being given to the sky than to the foreground.
(See Holder, Plate.)
(See Plates, Lantern.)