Piece of Rope in Place
Home-Made Motion-Picture Camera and Projector In Three Parts—Part II
Developing
After having exposed the film in the camera, the next steps are to develop and make a positive film from the negative. The developing and exposing of the film for the positive are the same as in ordinary photography for making negatives and lantern slides, the only difference being in the apparatus for handling the long films. One of the simplest ways of developing a long film is to use a large tray in connection with a cross arm having upright pins around which the film is wrapped in a continuous spiral. A film 100 ft. long would require a tray 18 by 22 in., with pins set in the cross arm about 3/8 in. apart. This method of developing is shown in Fig. 4.
Fig. 4—Cross Arms with Pins
A long film can be developed in a small tray by using two flanged wheels or spools mounted on a frame (Fig. 5) that holds them directly above the liquid in the tray. The spools have a wood core or center with metal sides of sufficient diameter to take in the length of film to be developed. One end of the undeveloped film is attached to one spool and then wound upon it, then the other end is passed through the guides, gelatine side down, and fastened to the other spool. The film is first run slowly through a water bath until it is thoroughly saturated, then it is passed through the developing solution again and again until the proper density is secured. The trays can be easily removed and others substituted for fixing, washing, hardening and soaking, the film being passed through each solution in the same manner. Before developing either negative or positive film, small test strips should be run through the solution so that the proper timing and treating of the full-length strip will correspond to the test strip.
