In a preceding chapter we have referred to the delineation of the pictures created by the Kaleidoscope, when they are received on the ground glass of a camera obscura, or when a camera lucida is placed at the eye-end of the instrument. Both of these methods are very imperfect, and when the pictures have been copied for useful purposes, we believe that they have generally been executed by a skilful draughtsman, who delineated carefully one of the sectors of which the figure is composed, and then repeated it so as to complete the picture.
Fig. 52.
Since the invention of the Kaleidoscope, the discovery of the photographic art—of the Daguerreotype and Talbotype processes, has given a new value to the instrument. By means of a Kaleidoscope Camera, the most complex figures can be almost instantaneously transferred to paper, or to plated copper, and hundreds of designs offered to the choice of the artist who is to employ them. The very same figure which is obtained by one mode of illumination, may be altered indefinitely, by merely changing the direction or the intensity of the light, all the objects which give the figure remaining fixed in the object-box. The optical arrangement by which these figures may be copied, photographically, is substantially the same as that which is shown in [Fig. 52], where C G D F is the Kaleidoscope, A O the object-box, and L L a small achromatic lens, of rock crystal or glass, a quarter of an inch in diameter, placed in contact with the extremities of the glass or metallic reflectors, and having its centre immediately behind the small opening at E. When the rays of the sun, or any other strong light, containing the actinic rays, are thrown obliquely upon the object-box A O, an image of the Kaleidoscopic figure, produced by the objects in the object-box, will be formed at P P, in the focus of the lens L L. If the focal length of the lens L L is equal to one-half C G, the length of the Kaleidoscope, the image will be formed behind L L, at a distance equal to C G, and of the same size as the object-box; but if the focal length of L L is greater than the half of C G, the image will be formed at a greater distance than C G, behind the lens, and the size of it will be greater than that of the object-box, the distance and the size of the picture increasing as the focal length of the lens increases; and when it becomes equal to C G, the size and the distance of the picture will be infinitely great. When the focal length of the lens is less than half C G, the figure will be smaller than the object-box, and nearer the lens.
The Kaleidoscope Camera.
Every camera employed for the purposes of photography may be readily adapted for taking the pictures formed by the Kaleidoscope. We have only to take out the lens or lenses which belong to it, and place the Kaleidoscope furnished with its lens L L, [Fig. 52], in the inner tube, which is movable by means of the rack and pinion. If the picture can be made distinct on the grey glass by the rack and pinion, a negative or positive copy of it may be taken on collodion or paper, in the same manner as other photographs. In some cameras the end of the box which contains the grey glass is movable, backwards and forwards, so that the adjustment for rendering the picture distinct may be effected, though the Kaleidoscope is fixed in the front portion of the box.
When the camera is made for the express purpose of taking Kaleidoscope pictures, it becomes a very simple instrument and may be constructed easily and cheaply. It requires no lens excepting the small one L L of rock crystal or of glass, a quarter of an inch in diameter. The aperture required for this lens is so small that the spherical and chromatic aberration cannot injure, in any sensible manner, the distinctness of the picture. The difference between the chemical and luminous focus, which cannot be made to coincide with a single lens, may be easily determined by experiment, or in order to avoid this, the small lens may be made achromatic.[16]
The form of the camera as fitted up with one of Mr. Bate’s Kaleidoscopes, with metallic reflectors, is shown in the annexed figure, where M C D N is the body of the camera, m n o p the tube which is moved out and in by a milled head attached to the pinion which drives the rack on the tube m n o p. The Kaleidoscope A B L L, exhibiting the figure which is to be copied, is temporarily fixed in this tube by pieces of cork or wood, so that its axis, or the line of junction of the reflectors, may be perpendicular to the surface of the grey glass p q, which can be taken out, so as to allow the collodion or paper slide to be placed in the same groove.
Fig. 53.
