UNQUESTIONABLY the enormous popularity that photography has attained during the last few years is largely due to the introduction of films. Both flat films and the newer daylight loading roll films have contributed to this popularity, for the introduction of celluloid as a base for the sensitive gelatine emulsion has enabled the traveller and the holiday-maker to add a camera and an adequate supply of material to his outfit without, as hitherto, burdening himself with a dead weight of glass plates, which are at once an incubus and an annoyance. The ever-present dread of breakage through careless handling, the constant necessity of obtaining dark-room accommodation, an accompaniment to the holiday which the roll film has almost abolished, all tended to increase the troubles of the amateur photographer, who has ere now discovered that it is just as possible to get perfectly good negatives on films as ever it was on glass plates and with none of the attendant risks.

The danger of halation has also been practically banished by the introduction of films. With a glass plate, unless it is properly backed with a soluble caramel backing or paint, there is an amount of halation which renders it difficult, or impossible, to secure good effects against the light or where there are violently contrasting lights and shadows, such as the outline of masts against a sunset sky or the delicate tracery of twigs and leaves in a landscape scene. For interiors the unbacked plate is absolutely useless if windows are to be included, and there are many other drawbacks which only the unfortunate user of unbacked plates discovers. The celluloid basis of a film is so much thinner than even the thinnest glass plates, that this trouble of reflected light is practically non-existent. No backing is required except in the most extreme cases, and seldom, if ever, is there more than the slightest trace of halation even with very troublesome subjects. The saving of weight and storage space, either before or after development, are advantages that do not require to be urged, as they are patent to the most casual observer; but it is not until one has accumulated a large stock of negatives both on glass plates and celluloid films that the really marvellous saving of space is quite realised.

Films, then, have the advantage of being lighter, less liable to breakage, take up less storage-room, and do not produce halation. They are a little dearer than glass plates, but the other advantages perhaps outweigh that. With roll films the price rises to rather more than double that of a backed plate, but the difficulties of manufacture must be taken into account, and the incalculable advantage of being able to dispense with that holiday bugbear, the dark room, both when loading and unloading the camera, are surely enough to justify the extra expense.

As some of the readers of this article may still be unwilling to concede the advantages already enumerated, there are still one or two more points in favour of the celluloid film. Being light and flexible, they may be sent by post in an ordinary envelope with little or no packing; and this should appeal to any amateur who is in the habit of sending his negatives to some trade retoucher or to have enlargements or prints made. Films may be printed from both sides, which does away with the need for double transfer in carbon work. Some of those workers who are so wedded to the use of glass plates that they will not admit that celluloid films can ever approach them say that one of their principal objections to films is that they do not keep well. Perhaps before development in hot climates they do not, but after development they will keep indefinitely, providing, of course, that they have been properly fixed and washed. The deterioration before development is only found in exceptional cases, and even plates have been known to fail in the same way.

Flat films are cut sheets of celluloid coated with sensitive emulsion and made in the same sizes as glass plates. They are put into an ordinary carrier, dark-slide or changing-box, just in the same way as a plate, and in the subsequent operations of development, fixation, and drying there is no special treatment required. Certain developers must be avoided, and rapid drying with alcohol would prove fatal owing to the fact that the celluloid would probably dissolve away. Both pyro-ammonia developer and acetone are liable to play havoc with films. The three A's—acetone, ammonia, and alcohol—therefore, had better be avoided, while yet another A, the acid fixing bath, is inadvisable.

The rest of this chapter will be devoted to the use and treatment of the deservedly popular roll film, and will endeavour to show how, with intelligent treatment, the roll film can produce not only perfect negatives, but can be manipulated with both celerity and certainty.

Photographers who are accustomed to handling plates and flat films frequently complain that they have great difficulty in making the short sections of rollable films keep under the developing solution, and many and curious are the devices that have been adopted to secure this end. Some of them, although undoubtedly ingenious, are more trouble than they are worth, as the reader will no doubt discover if he attempts to use them. One writer recommended the use of a wood-bottomed dish, and suggested pinning down the four corners before pouring on the developer. Another man states that he keeps his film sections flat by placing coins on the edges of the film, but he acknowledged that the rocking of the dish was apt to dislodge his makeshift weights, and the remedy was almost more trouble than the original complaint. Personally I never had any serious trouble in keeping the films quite flat when developing them in short sections, which is due to the fact that I always gave them a long preliminary soaking before attempting to start development.

We will suppose that a spool of a dozen has to be developed, and the nature of the exposures, or the inclination of the exposer, demands that they shall each be treated separately. The seal is broken, and the black paper is gradually unwound until the white sensitive material can just be seen by the light of the red lamp. Turn the spool over in the hand, and then with a pair of scissors make a good clean cut along the white line that marks the division between exposures eleven and twelve. In unwinding, the film must be held firmly in contact with the black paper, care being taken not to let it slip over the paper as it unwinds. Section number twelve will be rather longer than any of the subsequent sections, and this should be noted so as to avoid cutting into the exposed surface in number eleven. Experts may think this is a needless piece of advice, but one does now and then hear of films damaged by being cut off badly, and it should therefore be borne in mind. Each of the sections as it is cut off should be dropped into a deep ewer or bowl of water and left to soak until required, and the winding spool, with such black paper as remains, can be thrown away. By following these instructions it will be found that the cut-off pieces of black paper roll up above the sensitive film and can be secured with the first finger and the thumb of the left hand, so that they do not drop into the water as well. Now cover the ewer up carefully and get the developer ready. A deep dish should always be used, and plenty of developer. It is no good attempting to use two or three ounces for a quarter-plate film in a 5x4 dish, because you are simply courting disaster. With eight ounces you have a far greater chance of success, and then if your film does not keep quite flat there is room for it to arch up a little and still not get above the surface. We will now suppose everything is ready, and you have dipped into the ewer for a film.