STAND CAMERAS : COMMERCIAL, PROFESSIONAL, AND SEMI-PROFESSIONAL 148. General Notes. The photographic camera no longer inherits the primitive simplicity of the Daguerreotype box, to which the familiar term " camera obscura " could be strictly applied, and which consisted of a box into which light was admitted only through the lens placed in the centre of one of its sides.
Hand in hand with the successive improve ments in photographic processes, their uses increased infinitely, and thus different types of camera were evolved, each differing to a greater extent from the original form, until, externally at least, they no longer have any character in common, each being designed for a special purpose. This specialization, which is inherent to all progress, leads us to classify the various types of camera according to the purpose for which they are more chiefly intended.
It is obvious that with a camera for photo graphing stationary subjects or posed sitters, the conditions to be fulfilled are very different from those requisite in an instrument for taking instantaneous views or for photographing un observed a person or animal.
The former, which are intended for com mercial or studio work, are generally made in large sizes, without regard to bulk or weight, at any rate within certain limits, since they are intended for use on a rigid stand, and will not be carried from place to place except for special reasons. The latter need to be easily concealed, and will, therefore, always be of small sizes. If they are to be of the utmost service to the user they must be light enough to be carried about constantly, so as not to risk missing any interesting and unexpected subjects.
The stand camera will vary, as regards the different movements embodied in it, according as it is intended entirely for studio use (in copying flat originals, photographing articles for catalogue illustration, or for portraiture), or, as it is chiefly for use out of doors, in commer cial photography, architectural or landscape work.
While this is a somewhat arbitrary division, we will confine this chapter to the description of cameras solely for indoor use, and of those which, while portable, are intended exclusively for use on a rigid stand. In the next chapter
we will describe cameras generally used in the hand, though suitable for use also on a light stand.
We shall confine ourselves to a brief descrip tion, referring the reader to the makers' cata logues for details.
149. Names and Functions of the Parts of a Camera. A camera consists essentially of two bodies, of which one (the front) supports the lens flange, while the other (the back frame) receives alternately the ground-glass screen, on which focussing is done, and the dark slide in which the light-sensitive material is carried from the dark room to the camera and back again. These bodies are connected by a bellows, similar to the bellows of an accordion, made of cloth or leather, which allows the distance between the two bodies to be varied over a considerable range,' while shutting out all light except that admitted through the lens.
The lens flange is not fixed directly to the camera front, but to a lens board or lens panel, which slides in grooves permitting it to move parallel with itself upwards or downwards (vertical rise) or towards the right or left (cross front). Several interchangeable panels can each receive the flange of one of a series of lenses in use. 2 The two camera bodies are guided parallel with each other in grooves fitted in the base board. One or other of them is sometimes fixed permanently to this baseboard. The movement of the movable body (or of the two bodies) is generally done by two pinions mounted on one rod. These pinions engage in two racks fixed parallel with the optical axis. Helicoidal racks (with oblique teeth) afford a finer movement. When both bodies are movable, the front one is often arranged to be moved directly by hand. In better-class instruments it is often controlled by a winch-screw fixed along the longitudinal axis of the baseboard. In every case it is neces sary to be able to fix the bodies firmly in the position reached in the course of focussing.