The Educational screen (c1922-c1956])

Page 12 The Educational Screen as seen in the ground glass is the same size as it will he on the negative and very much as it will look on the final contact print. In addition, for copying, the camera should have at least a double bellows extension to per- mit real close-up work without auxiliary attachments. 6. Do I want a camera that takes interchangeable lenses, that is, lenses other than the one with which the camera was originally provided? There are occasions when lenses other than the standard one are advantageous, or even necessary, such as telephoto lenses for "close-ups" at a distance or wide-angle lenses that will cover a greater area. 7. JVhat sice negative do I want )ny camera to take' Negative sizes may vary from 35 mm. to 8" x 10", or even larger. Any camera will take pictures of only one size, or, in some cases, two at the most. Miniature cameras and larger cameras each have their advantages and disadvantages. In general, they may be summarized as follows, although it must be re- membered that all the items do not hold true for all cameras. Advantages of Miniature Cameras a. Convenient to carry around because they are small and do not weigh much. b. Less noticeable, making it easier to take so-called "candid" shots. Any size camera, it should be noted, if it has a reasonably fast shutter speed and lense, will take a candid picture, provided the subject is not aware the picture is being taken or does not pose. c. Ultra fast lenses, usually' found only on miniature cameras, make possible snapshots under unfavorable light conditions. d. The short focal length lenses that are standard for miniature cameras have great depth of field. e. Film for miniature cameras is inexpensive. f. The 35 mm. size is very convenient for making filmstrips. Disadvantages of Miniature Cameras a. If big enlargements of excellent quality are desired from the small negatives, a good miniature camera is needed, and good ones cost considerable money. b. Do not have shifting lens fronts and shifting backs for correcting distortion. c. Not particularly good for portraits. d. To obtain consistently good results with a minia- ture camera it is necessary to develop considerable skill in using it and to exercise great care in processing the negatives and in enlarging them. e. Because the contact prints are too small to be of much practical use, enlargements are necessary. The added expense of the more frequent enlargements to some extent nullifies the advantage in being able to use the relatively inexpensive film. f. Difficult to retouch the small negatives. Advantages of Larger Cameras a. A cheaper large camera will do as good a job as a more expensive miniature camera and with less trouble. b. Lenses to give negatives that will produce satis- factory big enlargements can be obtained more cheaply because they need not be as good. The negatives are large to begin with and so it is necessary to enlarge only a few diameters to obtain big enlargements. c. Lasy to make a .satisfactory enlargement. d. Less skill required for negative processing. e. Easier to retouch negatives. f. Shifting lens fronts and shifting backs available on some cameras. g. The large-size ground glass found in certain of the larger cameras permit careful composition. h. Better for portraiture and architectural studies. Disadvantages of Larger Cameras a. Inconvenient to carry aroimd because of tlieir large size and weight. b. Because very fast lenses are unavailable, they are not as useful for snap.shots in poor light. c. Not as convenient for candid work. d. The long focal length lenses used on the larger cameras have a shallow depth of field. However, this shallow depth of field may become an advantage in cer- tain cases, such as when it is desired to blur a back- ground. e. Most of the larger cameras cannot be adapted for the making of 35 mm. filmstrips. 8. Do I want to be able to develop my negatives, or to change to other type films, before the roll is com- pleted? Tiien a camera that takes cut film or film pack is needed. 9. Shall I watit to use my camera for special work, such as copying, photographing through a microscope, nncrophotography {photography oj small objects), scientific ivork, etc.? The camera must be of the kind that can do these special kinds of work and that will take the necessary accessories. 10. What type joctising do I want on my camera? Cameras may be divided into several classes depend- ing upon their focusing arrangements (all these types may be obtained in several sizes) : Fi.ved-jocus Cameras. These require no focusing— all objects from a few feet to infinity are in reasonably sharp focus. Examples are the box cameras and their ".stream-lined" versions. Non-automatic Focusing Cameras. These cameras have to be focused but they have no focusing device outside of a distance scale on the bed of the camera or around the lens assembly. The distance has to be esti- mated or measured and the lens set at a point on the distance scale corresponding to the actual distance. Coupled Range-finder Cameras. A range finder is a device for determining distance accurately from the camera position. When looking through the range finder, one sees a double image or a split image of the subject. By manipulating the adjustment on the range finder the two images, or the two halves of the split image, can be made to coincide. The correct distance may then be read on a scale. If such a range finder is coupled to the lense of the camera, the lens moves back and forth as the range finder is manipulated and when the two images of the subject (coincidence type range finder) or the two halves of the image (split-field type) coincide in the peep window, the lens is automatically (Conlinued on page 28)