13. Obtaining Perpendicular Lines

Obtaining Perpendicular Lines. To help you to determine when you have your lines as true as possible, draw a top and side line, with pencil and straight-edge, 3/4 of an inch from the top and side of ground-glass frame, on ground side of the glass. These guides will attract your attention to the lines of your object and enable you to get them perfectly true and perpendicular on the plate.

14. Double Swing

Double Swing. The modern professional view camera is fitted with double swing. The swing will permit of great inclination, being hinged at the bed or pivoted at the center of the back section. The swing-back is absolutely necessary as it not only assists the working of the lens, but permits the photographing of some buildings which would be impossible without the swing-back.

15. Rack And Pinion For Focusing

Rack And Pinion For Focusing. The rack and pinion movement is an additional improvement to the ordinary camera. With it, focusing is greatly simplified as the cog teeth are very close and fine, thus permitting more accurate focus to be obtained. With the hand camera the rack and pinion is attached to the bed and the racking is to the front. On professional view cameras some manufacturers have it attached to the front, others at the rear. Both methods are good, one having no advantage over the other.

16. Reversible Back

Reversible Back. The object of the reversible back is to enable the worker to make either horizontal or vertical views without changing the position of the camera. The back is held in place by means of firm clamps which are easily released when desired. The ground-glass is attached to the frame of the reversible back and for convenience of centering the object on the plate, there should be a vertical and horizontal line drawn through the center of the ground-glass, as we have previously instructed. It is also a good plan to mark the ground-glass for different size plates so that when plates of a smaller size are used the lines of the view may be easily located on the glass.

17. Lenses

Lenses. For architectural photography lenses with extreme depth of focus must be used. The ordinary Rapid Rectilinear Lens will, therefore, serve for all ordinary work. There are times when photographing interiors, tall buildings in narrow streets, and working in closely confined places make it necessary for a wide-angle lens to be employed. For these reasons every camera should be equipped with lens of this character that it may be attached instantly when occasion requires.

18. There are also times when objects are to be photographed at long range. For instance, cornices of tall buildings, moving ships at quite a distance from shore, objects on the opposite side of a river; in short, photographing anything at a distance too far away to obtain a satisfactorily large image upon the plate with an ordinary lens. In such cases a Telephoto Lens is of wonderful assistance. The specially constructed Telephoto Lens, which is a very long focus rectilinear instrument, is not in general use by photographers. However, the convertible three-focus lens is very much in use and serves as an excellent all-around instrument. It is used quite generally for ordinary telephoto work. (See Illustration No. 12, Page 51).

NOTE: - Detailed information regarding all classes of lenses and shutters will be found in Vol. VI.