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.
By M. J. Shiels.
Introduction. Serious workers frequently refuse to consider the hand-camera otherwise than suitable for recreative work, owing to the uncertainty of the results it yields, and leave it out of consideration for professional work. The aim of this article is to demonstrate how these objections are entirely overcome in the Reflex cameras, which, although hand-cameras in the strictest sense of the word, give a greater control over the combined operations of focusing and exposing than is obtainable with tripod cameras of all types.
Essential Feature Of The Reflex Camera. The essential feature of the Reflex camera consists in the placing of the ground-glass in the top of the camera, whereas film or plate occupies the usual place in the back. A mirror placed at an angle of 45° to the plane of the sensitive plate or film reflects the image from the lens to this ground-glass. This arrangement permits of having the ground-glass and the plate both ready in their operative positions at the same time, whereas in tripod cameras the insertion of the plate or film renders the ground-glass inoperative.
Ready For Instant Exposure. In all cases where continuously moving objects are to be photographed, the time required to insert the plate renders the previous focusing useless, as at the time of the exposure the objects may have approached toward or receded away from the lens sufficiently to require a different adjustment of the latter. The Reflex construction permits of focusing up to the very instant of exposure, and is thus really the only practical instrument for this kind of work.
Compared With Twin-Lens Cameras. It may be said that twin-lens cameras perform the same service, but this is not so in practice nor in theory. The finder lens of a twin-lens camera, usually placed above the photographic lens, never shows the same picture as that which will be developed on the plate, owing to the different position of the finder lens. Particularly when the subject is nearby will the difference in foreground as shown and as photographed be sufficient to produce faulty results.
556. As a twin-lens camera is bulkier, and neither simpler nor cheaper than the single lens Reflex camera, which shows under all circumstances exactly what will appear on the picture, it is easily understood why this latter type of construction is so universally preferred.
Focusing Hood. In order to obtain full advantage of the focusing facilities of the Reflex camera the focusing hood has been most carefully designed. It is of sufficient length to permit of placing the eyes directly on it. The hood itself is perfectly rigid when extended, and its top is provided with a plush-covered flexible eye-piece, fitting tightly around the eyes and completely excluding all outside light. It shows the ground-glass from corner to corner, and the image appears with its full brilliancy, enabling the operator to focus quickly and with precision. Even with a diaphragm stopped down to f. 16 the image has all the necessary strength to allow accurate focusing. This would be impossible if its brilliancy should be dimmed, by light entering through the focusing hood.
558. The necessity of a hood which completely excludes the outside light becomes most evident when the light on the subject is extremely bright, as in plain bright sunshine views on the water, and snow scenes. When looking at such scenes the pupil of the eye contracts to a small opening, thereby preventing one from seeing the image immediately and focusing accurately unless that image is perfectly sheltered and protected from false light. Only a close-fitting hood, as provided on the Reflex cameras, will properly cover this condition. A further material advantage offered by this construction, is that the forehead is used to steady the camera instead of the chest, insuring thereby increased steadiness.
Illustrations Nos. 45 and 46.