Page:EB1911 - Volume 21.djvu/530

Rh together with the copying board, on swinging stands, to avoid the effects of vibration.

Portable and field cameras include cameras of the Hare and Meagher types for outdoor work and general purposes on plates 15 in. ✕ 12 in. to 8 in. ✕ 6 in., and in lighter forms from 6 in. ✕ 4 in. to 4 in. ✕ 3 in. For general purposes they are usually made with square bellows and folding tail-board, rather more substantially than those with conical bellows intended for outdoor work. There are many patterns, the principal modern improvements in field cameras being swinging fronts, tripod head an turntable in the base-board, double and sometimes triple extension movements from the back and front for long or short focus lenses, and the use of aluminium for some of the metal-work. They are fitted with a focusing screen and are intended for use on a tripod stand, though some of the smaller sizes of the modern light han or stand cameras can be used as hand cameras with finders. The plates are carried in the usual dark-slides, but the smaller sizes, from half-plate downwards, can be fitted with roll-holders for flexible films, or with film packs or other daylight changing arrangements.

.Folding and Hand Cameras—Folding cameras form a class of modern portable cameras which have many conveniences for hand

or stand work from quarter zip late to 7 in. ✕ 5 in. hey may have all the fittings of a stand camera and be made to take glass plates, fiat or roll films, but have the advantage of forming when closed a convenient package enclosing camera, lens and shutter, all in position for immediate use when opened out (fig. 2). Most of them are fitted with focusing glass and finders, and may focus by scale in the same way as hand cameras. With an apparatus of this kind on a light stand any class of ordinary indoor or outdoor work can be undertaken within the size of the plate, and the extension of the bellows, which should be quite double the focus of the lens.

The multiplicity of forms and arrangements of hand cameras makes it difficult to classify them into distinct types; but they may be mainly divided into box and folding cameras, and further into (a) cameras with enclosed changing magazines for plates or flat films; (b) with enclosed roll film on spools; (c) with separate changing magazines, changing boxes or roll-holders; (d) with single, double or multiple plate carriers or film-packs. Most cameras that will take glass plates in the ordinary plate-holders will take cut films in suitable sheaths or can be fitted with envelope slides, film-packs or roll-holders. The normal size for hand cameras is the quarter plate (4 in. ✕ 3 in.), or the continental size 9 ✕ 12 cm.; 5 in. ✕ 4 in. is also a popular size, and cameras for the post-card size, 5 in. ✕ 3, in. or 15 ✕ 10 cm. have been largely adopted. Smaller sizes are also made for lantern plates and for the lighter pocket cameras, some in the form of stereoscopes, field-glasses or watches, as in the “Ticka,” but the pictures are small and require enlarging. Hand cameras are constructed on the same principles as stand cameras, but, being specially intended for instantaneous work, they are simplified and adapted for rapid focusing and exposing. The focusing screen is superseded or supplemented by finders arranged to show the limits of the subject on the plate, the focus being adjusted by the infinity catches and focusing scales above noticed. Swing-backs and fronts are often dispensed with, but are desirable adjuncts, and a rising and falling front particularly so. Lenses of fairly large aperture, f&#8198;/6 to f/8, and good covering power, preferably of the an astigmatic type, or a rapid aplanat, should be used, but for very rapid work anastigmats working from f/4 to f/6 will be more useful. Hand cameras can also be fitted with telephoto objectives of large aperture. Some cheap hand cameras are fitted with single landscape lenses or aplanats working about f/11 or lower, but the want of intensity limits their use to well-illuminated subjects. Shutters of the between-lens type are now generally used in hand cameras, and for ordinary purposes should give fairly accurate exposures from to  of a second or less and also time exposures Some central shutters are speeded for shorter exposures to of a second, but for these focal plane shutters are pre erable, an for the more rapid exposures to, of a second and less are necessary. The shutter should be efficient, regular in action, and readily released by gentle pressure, pneumatic or otherwise. Mechanism for automatically changing plates or films in hand cameras of the box magazine type must be certain in action, simple and not readily put out of order, special care being taken to avoid rubbing or abrasion of the plates in changing or transport. In changing plates or films the number of plates exposed should be recorded automatically, and duplicate exposures prevented as

far as practicable. A circular level placed near the finder is useful.

The choice of a hand camera depends upon the circumstances in which it is to be used, and the purpose for which it is principally required. For general work and with the modern facilities for carrying and changing plates and films in daylight, the numerous folding hand or stand cameras for plates, fiat or roll films, with full adjustments, will be found most useful. Box or magazine cameras in which a supply of cut films or plates can be carried, changed mechanically, and exposed rapidly in succession, are convenient, but their use is limited and they are liable to get out Of order.

. 3.—Ernemann’s Pocket Camera. A third class are the reflex and other hand cameras with focal plane shutters for specially rapid instantaneous work as noticed below. There are two types of light folding hand or stand cameras, specially adapted for hand camera work—those made for taking glass plates and cut films, and the folding pocket Kodak or other roll-film cameras. The former are now made of verfy light construction with mahogany or metal bodies, wooden or aluminium baseboards, thin metal dark slides (fig. 3). The cameras of the pocket Kodak type are of similar construction, but made to take roll films on spools, or with an attachment for focusing glass and dark-slides for taking plates and cut films. Attached to a sling-strap the quarter-plate size can be quite conveniently carried in a side-pocket. Watson’s “Deft”

. 4.—The “Deft” Folding Focal-plane Camera. folding camera is fitted with a focal plane shutter (fig. 4). The “Selfix carbine” camera has a self-erecting front bringing the lens at once into position for use on opening out. Those fitted with lenses of fairly large aperture, double extension, and rising and falling fronts are to be preferred. Of box or magazine cameras there is an immense variety. In some the lens is fixed in focus for all objects within a certain distance, in others it is adjusted by a focusing scale on the lens or by an extending front. Some have a single magazine, others two or more. Some take only glass plates, others plates or cut films. All of them are, however, self-contained and ready for immediate exposure. One of the earliest forms of single magazine cameras, still in use, as in the “Eureka” and “Yale,” is the “bag,” in

. 5.—Double-magazine Box

. 6.—The Verascope, Richard. which a supply of plates or films in sheaths, is kept in a magazine behind the camera, ready for exposure, the plates as exposed being lifted with the fingers into a bag or expanding chamber above the magazine and placed behind the rest of the plates at the back, a fresh plate taking its place in front. In some forms the magazines are removable and replaceable by others. The arrangement is simple and effective, but the bag, usually made of soft leather or cloth, is liable to wear and puncture, and may make dust. The cameras with double magazines in which unexposed plates are kept in one recess and transferred successively after exposure to a second recess are more complicated, and many 