Turning the driving handle is no more difficult than turning that of the camera mechanism. The gearing is so designed that six exposures are made per revolution, representing twelve pictures per second, when revolved at the normal speed. With a negative of average density this speed is sufficient. But the period of exposure can be varied according to the speed at which the handle is turned. The turns of the handle should be steady and regular, or the pictures will be of uneven density owing to the variations in exposure.
The electric light is easily moved by means of the handle while the ten stops give it great flexibility. In order to maintain an exposure of twelve pictures per second with an average negative, a lamp of 50 candle power should be used. To ensure the best results it should be of the class known as "focus lamp." This type of lamp has a special filament, with a smaller coil than is found in the ordinary incandescent electric lamp. A gas burner with incandescent mantle may be used if electricity is not available, though the operator will have to ascertain the relative value of the luminous intensity of the light as compared with the 50 candle power electric light, and will be wise if he makes one or two trial exposures with short lengths of film before essaying the printing of a complete film.
While it is possible during printing to vary the distance of the light from the exposure window, the light being manipulated with the left hand, while the handle is turned with the right, there is slight necessity for such a procedure. The negative film should be examined to ascertain how the density varies along its length, and then each portion of film that shows tolerable regularity of density should be printed off at the same speed. In this way variations of distance need occur only with distinct lengths of film. This is a far safer method, especially for the beginner, than the movement of the light to and fro while the films are running through the gate, though of course with practice it becomes possible to do the two things satisfactorily at once. Many amateur cinematographers make the mistake of attempting artifices which they have seen practised by some experienced professional worker, and the result is failure. What is easy and simple to the expert is often beyond the powers of the beginner. Success in printing can only be achieved by honest and diligent work, but patience is sure of its reward. At first there may be a tendency to make the positives somewhat too dense, and then, when the evils of this defect are appreciated, to fly to the opposite extreme. Of the two blemishes probably the latter is the worse, as it produces a washed-out effect upon the screen.
The positive is developed in exactly the same way as the negative, and with the same solutions. When dry the positive, which may have been printed in short distinct lengths, should be connected up with the aid of cement as described in a previous chapter. If titles have to be introduced they may be inserted wherever required, merely by severing the film at that point, and introducing the length carrying the explanation.
The preparation of the titles is a simple matter. If printed type is used, the letters cut out of white paper or cardboard are laid flat upon a level surface with a black background. The camera is then placed overhead with the lens pointing downwards upon the centre of the title space. The latter, brilliantly illuminated, is then photographed at the rate of sixteen pictures per second for a period of ten seconds or more according to requirements.
In many instances, especially in non-topical work, the operator need not necessarily incur the expense and trouble of printing a positive film. Many of the purchasers of educational and popularly scientific films will give their decision after having seen the negative passed through the projector in the manner of a positive film. So long as great care is used, this can be done without ill effects, but of course the slightest scratch or abrasion that the negative may receive in the process will be reproduced with accentuated effect upon the positive film. Even with some of the topical films a positive is not necessary. To submit the negative to the local theatre or prospective purchaser is often a good way of saving time and being first in the field. Many theatres now are being equipped with dark rooms and printing machines. A glance at the negative will enable the manager to decide whether the film is serviceable or otherwise, and if a purchase is made, the deletion of the uninteresting parts can be made before printing. Incidentally, one great advantage of this is that the film is submitted for consideration about three or four hours earlier than would be the case if the independent worker struck off his own positive, and in these days of high pressure such a saving is important. It may often be the means of forestalling a competitor. Even if it is intended to supply prints to two or three different picture palaces the negative offers a means of transacting business, because the respective establishments can give their orders, make their arrangements concerning announcements, and be able to judge fairly accurately the hour at which the film will be available for projection. In one instance an independent topical worker who had a first-class negative of a popular subject drove round from theatre to theatre with his negative and secured an order for about half-a-dozen copies. He then handed over the work of printing to a professional firm. Four hours later he delivered the positives to the respective theatres, and ultimately he sold the negative outright to the firm who completed his printing contracts for the supply of other markets at their disposal. In another instance an enterprising amateur who had an excellent negative handed it over to a topical-film firm to print and circulate, the firm to take fifty per cent. of the receipts and to bear the expense of printing and other details.