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 Swing-Back Properly. Having attached the camera to a carefully leveled tripod, you will find that the axis of the lens is in the center of the ground-glass, but the top of the building and sky line are cut off. (See Illustration No. 14).
57. By reference to Illustration No. 14, showing the camera placed perfectly level, you will note that line C leading from the base of the building through the lens to the ground-glass, comes within the range of the ground-glass, while line A leading from the top of the building extends beyond the ground-glass, the building being too high to be entirely admitted into the view. The dotted line leading from the edge of the ground-glass to the building indicates the portion of the building projected on the screen.
58. By reference to Illustration No. 15 you will see the effect of tipping the camera upwards in an endeavor to admit the entire building in view without using the swing-back or rising front. The rear of the camera containing the ground-glass is tilted backward and is not perpendicular with the building. The face is receding from point of sight and the image on the ground-glass will appear broader at the bottom than at the top. This is explained as follows:
Illustration No. 14 - See Paragraph No. 56.
Illustration No. 15 -See Paragraph No. 58.
Illustration No. 16 See Paragraph No. 59.
Illustration No. 17 - See Paragraphs No. 61-64.
Illustration No. 18 - See Paragraphs No. 61-64.
Illustration No. 19 - See Paragraph No. 69.
59. Line A is longer than Line C, for the bottom of the building is nearer the lens than the top. The nearer an object is to the lens the larger it will appear on the ground-glass. The top of the building being farther away will appear smaller than the bottom. The building if photographed with the camera in this position would result in the image being broad at the bottom and narrow at the top. See Illustration No. 16. This distortion is overcome with the use of the swing-back and rising front. If the camera employed has not the rising and falling front, nor swing-back attachment, the only way this building could be photographed to retain perfect rectilinear lines, would be to move the camera further away until with the instrument level the entire image would appear on the ground-glass. This, of course, would take much more foreground than desired, but is the only way the building could be photographed with a camera not equipped with these attachments.
60. If one could operate such a camera from some elevated point, thus dividing the space above the level of the camera with that below it, he would, of course, overcome considerable distance. If the camera is fitted with the rising front and swing-back attachment these difficulties are easily overcome.
61. With such an instrument, if you wish to include more sky or more foreground into the view without moving from your position, the front board containing the lens must be raised or lowered. In this case - see Illustration No. 17 - we have all the foreground desired, but require more of the top of building and sky, consequently, by means of the rising front, raise the front board and lens to a height that will admit the top of the building and sky to the required degree. If the bellows is square shaped, the rays of light will not be obstructed by the upper portion. If a cone bellows is used the front of the bellows as well as the lens must be raised, otherwise the bellows-folds will obstruct the rays of light. See Illustrations 17-18.
62. Illustration No. 17 represents a professional view camera with bellows and lens raised and swing-back tilted forward perpendicular with the building.
In Illustration No. 18 is shown a hand camera properly adjusted. Nos. 17 and 18 are practically the same with the exceptions that the one is a hand camera and the other a professional instrument.
63. When photographing extremely high buildings in cramped surroundings, or to admit more sky it may be necessary to tilt the camera upward. In other words, the entire front of the camera must be raised to an angle that will enable you to take in the entire building; or to secure as much sky as is necessary.
64. In order to retain your rectilinear lines it is necessary that the top of your ground-glass be pushed forward by means of the swing-back, parallel with the walls of the building you are photographing. (See Illustrations 17 and 18.) In pushing the swing-back forward, however, we meet the first difficulty. Just as soon as the axis of the lens is changed in relation to the ground-glass and the walls of the building, the sharper passage of light is disturbed, and to the eye appears distorted; but, with the proper stopping down and careful use of the swing-back perfect rectilinear lines will be obtained. It is therefore necessary, in order to retain rectilinear lines, that the ground-glass and swing-back of the camera be absolutely parallel with the walls of the building.
65. For the beginner, it is a good plan when photographing high buildings to first obtain your focus and lines as straight as you can get them without using the swing-back or rising front; then raise the front board sufficiently to admit the building and the necessary amount of sky into the view; and finally unscrew the clamp on the swing-back and tilt it backward and forward, noting the changing lines.
When you have them just right - parallel with the perpendicular lines on your ground-glass - fasten the clamp and you will have the building perfectly true on the plate.
66. Do not forget that in order to retain rectilinear lines, whenever you tilt the camera it is necessary to use the swing-back also. You will find, when using the swing-back, that the top of the building will be thrown entirely out of focus. This will be the case, particularly if the building you are photographing is extremely high, requiring an extreme use of the swing-back. In such a case focus for the lower portion of the building with an open lens, using no stop. Then slightly divide the focus between the bottom and the center of the building, and finally diaphragm (or stop down) with a stop small enough to bring the top of the building sufficiently into focus. You will thereby obtain sharpness in the remaining portions of the view.