The camera is generally sent out to meet the needs of professional operators, with a lens of the shortest possible focus. Whenever the light is good, and other circumstances will allow of it, we always prefer a long-focus lens, say 5 or 6 in., and whenever a film taken under such conditions is shown on the screen, the greatly improved perspective and truthful representation of real life is very noticeable. Set pictures can nearly always be arranged so that the actors shall keep within the narrower angle included by the long focus lens. In choosing a cinematograph camera, a pattern should be preferred which will readily permit of interchang ing lenses of varying foci ; also one in which the film boxes are conveniently placed. Another good point is a method of automatically marking off on the film any change of subject, or a place where the film can be divided if too long for development at full length. Most good instruments allow of the film being drawn backwards as well as forwards in the production of " Trick films." Anybody with experience in hand-camera work can soon become familiar with the requirements of the cinematograph picture-producer. The only serious difficulty he will en counter is in turning the handle which actuates the changing mechanism at a uniform speed, and without any jerks or abrupt stoppages. Much practice at home with an empty camera is advisable, keeping an eye on the indicator dial, and timing it with a watch, till one unconsciously acquires a rhythmical motion of 15 to 25 pictures a second. The so-called " Trick films " are produced at a much slower rate, enabling the actors to perform feats which, when the film is run rapidly through the projection lantern, appear abso lutely magical or ridiculous, as the case may be.
The Film.—The length of film may be anything from 8o to 500 ft. In width it is about 1,4 in., taking pictures each i x in., and about i6 pictures on each foot of film. At the usual rate of exposure 50 ft. of film pass through the camera in a minute, producing about 800 pictures. It is ally possible to break up events into separate episodes of about 125 to 150 ft. each, but nearly all cameras will run for 500 ft. without a break ; and one or two have a capacity for over t,000, or in other words, a minute story Development.—We are often asked by a kodak-user, conscious of how unmanageable a plate film of twelve exposures can become in the dark room when wet : " How on earth can you develop a hundred and fifty feet of film ? You tell us you have done it in an extemporised dark room in a guard's van, on the journey between Liverpool and Euston." And yet, given the proper appliances, the task is very simple. Once upon a time we used to wind the film round a large wooden drum which revolved above the developing dish. The bother of this was that the developer was exposed so much to the air that its oxidisation produced stains, unless one was very careful. Development was somewhat uneven, and it was necessary to work by a rather dim light. Then came the pin frame, which can be best
understood by the diagram. It consists of a kind of cross frame or wheel, of wood or metal, the spokes of which are studded with a large number of pegs. The one we use is two feet square and takes with ease i6o feet of film, wound carefully round the pegs sensitive side outwards, beginning at the centre. Our actual procedure is as follows : First we cut off two or three inches at one end, as a test with the developer, to see if the exposure is under or over the normal. According to the result of this preliminary test the constituents of the developer must be modified. We then make up a time developer (usually pyro or glycin) in quantity sufficient to fill a stoneware sink twenty-six inches square inside to a depth of about three inches, and immerse the film, frame and all. Pyro-soda is a good developer, especially when exposure has been rather short. It is well to create a little movement in the developing solution, lifting the frame up and down by means of the central handle.
When development is adjudged complete the sink is emptied through the drain, and three or four changes of water are poured in before introducing the fixing solution, after which the film is thoroughly washed, treated with a weak solution of glycerine and hung up, still on its frame, to dry. In hot weather it is of course necessary to commence operations with a moment or two immersion in formaline, one ounce to the pint.
Printing.—Many cameras are claimed by their makers to be available for printing the positive film by contact, but the danger of one film creeping upon the other, as they are drawn together through the apparatus, is very great. If the registration is once lost, the film is valueless for projection purposes, because the broken halves of two adjacent pictures will appear on the screen, the upper one showing legs walking about without bodies, and the lower one ending abruptly with the characters cut off at the waistband. Everything in connection with cinematograph work must be carefully thought out, and executed with scrupulous accuracy. A reliable printing machine cannot be obtained for less than about £35, and must provide against shrinkages in the negative film as well as slight variations of width. The claw movement is preferable. The printing is usually performed with the aid of a fifty-candle-power filament lamp printing from five to ten pictures a second. Development of the positive film follows the same rules as those described 1 for the preparation of the negative. Only, it must be re membered that the positive film is a kind of continuous lantern slide, and therefore a brilliant, plucky effect must be the aim in development—plenty of detail without great density or fog. Each of these little inch pictures may have to cover a screen of twenty or thirty feet, and therefore must allow of an enormous amount of light passing through them.