American cinematographer (Sept 1935)

beginner may want to shoot some positive stock in the camera and develop it before attempting the panchromatic negatives. Positive stock can be handled in quite a bright red light so that the worker can see what he is doing while the panchromatic film must be handled in a dim green light—or better still, without any light. A fairly good negative can be made on positive stock, except for color rendering, if it is given a soft development. Exposure for this film should be about the same as for regular panchromatic reversal in good light—a little more when the light is poor. Developing the Negative When the film has been exposed and ready for devel- opment, the lights are extinguished except the proper safe light and one end of the film attached to the drum with a thumb tack. The drum is revolved and the film wound between the spacing pins (emulsion side out, of course) until the drum is full or the end is reached. The end of the film is then fastened with a rubber band to the drum —the rubber band will take up the slack (film expands when wet), if the film is revolved in the developer in the same direction as when the film is wound on the drum. The developer is then poured into the tank and the drum revolved slowly so the film dips into the solution— only a small quantity of developer is needed with this system of development. The beginner should stick to a standard developer such as Eastman's D-76 which was developed especially for fine grain development of motion picture film. This formula developer can be bought ready to dissolve in water if it isn't desired to compound it and it will keep for months if bottled in an air-tight fruit jar or similar container when not in use. The formula is given below for those who want to mix their own; Metol - 60 grains Sodium Sulphite 7 ounces Hydroquinone 150 grains Borax 60 grains Water ’/2 gallon The regular panchromatic negative films are capable of great contrast—too great unless development is watched. Lengthening development time increases contrast, short- ening development time reduces contrast, other things being equal. By varying the length of development time a nega- tive can be made to suit the worker's idea of contrast altho the shorter development times will give finer grained nega- tives. The writer likes about 1 Vz minutes with the regular and 9 minutes with the Special panchromatic negatives when the developer temperature is 68°. The worker will have to decide for himself what degree of contrast he likes and alter his development time accordingly. After the film has been developing for about 5 minutes, a green safe light can be brought up close to the film for examina- tion, altho not much can be seen in the weak light. A straight time development is best, especially if a short test has been taken off the roll and developed before starting to do the whole roll. If that is done, the whole development of the negative can be carried out in total darkness so that all danger of fog is eliminated. When the development is complete, as determined by inspection or time, the film is transferred to the wash tank and revolved for a minute or two, then transferred to the hypo tank for fixing. Eastman's prepared acid fixing powder is quite satisfactory for this—one pound makes half a gallon of solution which will keep nicely in a jar when not in use. Revolve the film through the hypo until the silver bromide is completely dissolved away—after it visibly begins to disappear, the white lights can be turned on for the rest of the process. Complete fixing is desired, so do not rush the operation; again as long as it takes the film to visibly clear, is safe. After fixing, the film is washed thoroughly by re- volving it in the wash tank while water from a faucet is run into the tank with a rubber hose and allowed to overflow the tank. About 15 minutes of washing will be satisfactory, after which the film is run onto the drying drum. Loosen one end of the film on the developing drum and attach it to the drying drum. Wet the two pieces of viscose sponge and squeeze out as dry as possible. Place one piece of the sponge on each side of the film and re- volve the drying drum so as to pull the wet film off the developing drum through the sponges and onto the dry- ing drum. Press the sponges together firmly enough to wipe all surface moisture off the film—the hardener in (Continued on Page 408) /L /