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.
Placing The Original To Be Copied In The Proper Light.
In arranging the original picture or drawing in position for copying, great care must be exercised that the light does not come all from one side. To get an even illumination the original should face the light as much as possible. Unless this is done, the grain in the paper, no matter how slight it may be, will show very strong in your copy. Whether you are using artificial or day light, be careful that the light strikes the picture flat and illuminates it evenly. With a little experimenting, and carefully watching the effect of the light on the picture and your results, you will readily overcome this difficulty.
Making Copy Same Size As Original. If you are using a rectilinear lens and have a long bellows camera, you should have no trouble. Carefully measure the picture and then also measure the image on the ground-glass. If you have no long bellows camera supply yourself with either a reading-glass, or a copying-lens of the kind to be attached to your regular lens. A very good plan is to paste a strip of black paper, exactly 6 inches in length and about % inch wide, on the copying easel or support to which you have tacked your original picture. This should be placed on the side of the original and fairly near to the margin. If you desire to reduce your copy say to half its original size, all that is necessary for you to do is to adjust the focusing until the strip measures 3 inches on the ground-glass; or, if you desire to make it three-quarter size, adjust your camera until the strip measures 4 1/2 inches on the ground-glnss. This same method can be applied if you desire to make an enlarged copy.
Copying Water-Color Drawings. When copying water-color drawings you will find that, when compared with very dark oil paintings, a dark water-color would require only one-third the exposure, all depending upon the density of the colors.
Making Copies From Oil Paintings. When copying an oil painting never turn the picture upside down in order to focus it. A painting should be lighted from the same direction as the light used by the artist when painting it. One reason for this is that the painter had a motive in laying every brush-mark upon the canvas. Oftentimes you will find the paint is laid on heavily in order to give certain effects to the shadows which the brush-marks cast, so that if the picture is lighted from a different direction the purpose of the artist is confused. Another reason is that when lighted from the correct direction very little glare, if any, from the surface will be noticed. Sometimes it is necessary to place the picture at an angle to the window, with the result that the exposure must be prolonged. This arrangement of the picture will cause uneven illumination, which may be equalized by placing the picture well to one side of the window so that the near side of the canvas is slightly screened by the window casing. It is not a reliable test for reflection to place the head in front of the camera, because the light reaches the eye at a different angle to that at which it reaches the lens. The best plan is to focus the picture, remove the lens and ground-glass and examine from the position to be occupied by the plate-holder.
550. The choice of a suitable plate is a matter requiring careful judgment. There are many excellent brands of Orthochro-matic and Isochromatic plates on the market which answer well when fairly fresh but are liable to change their color sensitiveness when kept too long. You must also consider the penetrating colors and use the plate and color-screen which is most suitable.