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.
604. The lenses which are supplied with most small hand cameras are limited in their scope, and the amateur is often desirous of doing work which his lens will not accomplish. Of course lenses for particular purposes can be purchased, but generally speaking, they are expensive. However, the amateur can readily overcome this difficulty and fulfil his wants by the use of little extra lenses, which are commonly called "supplementary lenses." These are, practically, spectacle glasses ground to give, in conjunction with the lens on the camera, either wide-angle effects, short focus effects, long distance effects, and so on. Such supplementary lenses can be bought ready to slip over the regular lens.
Ideal Outfit. The Ideal Photo Optical Outfit consists of a complete set of ideal supplementary lenses, a ray filter and a duplicator. They are made to slip over the lens just like a cap, and are adjustable to any lens generally supplied with a 4x5 or 5 x 7 camera. With this outfit there is no limit to the variety of effects obtainable. The lenses are only supplementary, but they give the owner of an ordinary objective lens the advantage of five different focal lengths, which is equivalent to five objective lenses.
606. The outfit consists of one portrait lens, one enlarging and copying lens, one wide-angle lens, one telephoto lens, one ray filter and one duplicator. (See Illustration No.
67.) It is not necessary to purchase this entire outfit, as each lens may be bought singly. When purchasing any of these lenses, the diameter of your lens must be carefully measured and the size given, also the style, make and size of camera.
Portrait Lens. This lens is intended for making portraits or large heads, with a short bellows camera. It will increase the speed of your lens and give a softness to the image that is only obtained by the use of a regular portrait lens. Slip the attachment over your lens, and if the frame of the attachment fits too loosely, push the springs in towards the center, so they will hold firmly. The springs must all be pushed in the same distance from all sides, so that the lens in the attachment may be properly centered. Focus the camera with the supplementary portrait lens attached, using the largest stop. The nearer the camera is to the subject the larger will be the portrait. The exposure is made in the usual way. When ordering supplementary lenses, give make and size of camera, and also measure the diameter of your regular lens.
Enlarging And Copying Lens. This lens, when attached to the lens of any camera, will increase its power so that small objects or pictures may be photographed to their full size, or larger if desired. Draw the bellows of the camera out as far as it will go. Next slip the enlarging and copying lens over the front of your regular lens. Place the camera on a table about 6 inches from the object or picture to be photographed. Carefully examine the image on the ground-glass, and instead of focusing by pulling the bellows back and forth, focus by pushing the entire camera to or from the object or picture, until a sharp image is obtained on the ground-glass.
Illustration No. 67 Ideal Photo Optical Outfit.
See Paragraph No. 606
Illustration No. 68 Kodak Portrait Lens See Paragraph No. 618.
609. The above directions explain the method for securing the largest picture possible with this combination. If it is desired to make pictures of actual size or smaller, adjust the bellows until the required size is seen on the ground-glass, and then focus sharply, as described above. In all cases focus with a large diaphragm in the lens, but before exposing change it to a small one. This small stop will increase the depth of focus and cover the plate sharp to the corners. The small stop will, of course, make it necessary to give a longer exposure.