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.
Using The Copying-Board. Place the copying-board on a table, which must be as high as the window. If the table is not of the proper height, the board must be raised to a height on a level with the window, and the end of the board containing the negative placed close to the window glass. Then focus the negative on the ground-glass.
873. After obtaining the focus all surrounding light must be excluded, and only that which comes through the negative admitted. It is not necessary to darken the room entirely. Draw the opaque curtains; then in order to further exclude the light within the range of the lens, extend two strips from the top of the camera to the top of the printing-frame. Over these strips place an opaque cloth. Allow it to hang on both sides. In this way all the direct light except that coming through the negative is excluded. After obtaining the focus, make the exposure.
874. The negative-holder attachment to the copying-board may be done away with if desired and the negative-holder placed in the window. In this case have the edge of the negative-holder rest on the window sash, and hold it close to the window glass by means of a strong cord stretched across the window and on a line with the upper edge of the small printing-frame. The negative is then ready for copying, and you can use the copying-board without the negative-holder attachment, or your regular camera attached to a tripod or camera stand, and arranged before the window in exactly the same manner as if the negative-holder were attached to the copying-board. When the latter method is employed, the copying-board or camera must be on a perfect level and alignment with the negative placed in the window, otherwise you will be troubled with distortion. The use of the copying-board is, therefore, the best, as it is very easily constructed, all such difficulties are overcome, and the outfit is always ready for use.
Lens Necessary For Reducing. Any ordinary rectilinear lens fitted to a long bellows camera is all that is necessary. There is no need for an anastigmat lens, but of course any high-class modern lens can be employed, and has this advantage, that it can be used with a large stop, which will be found of great benefit, especially when artificial light is employed. When a hand camera is used a lens of about 5 inch focus is most convenient, as this does not make the whole arrangement unwieldy. A long focus lens will give equally good slides, but may require a distance between the negative and lens which would be somewhat inconvenient. If the bellows of the camera is not long enough, a supplementary copying-lens may be used; this lens fits over the regular lens employed, and enables you to use any camera for this work.
Proper Light For Making Slides By Contact. It is advisable to use an artificial light for making slides by contact; either candle, kerosene lamp, electric or gas-light will do, and frequently the simple light of a match will give sufficient exposure to print the slide.