15. Processing Films The special Microfile emulsion is developed in Stineman tanks, using full-strength Kodak D-76 developer at 75¥F, for 2.5 minutes. After devel- opment the film is placed in a short-stop solution, and then is fixed and Drying is accomplished in air, without forced drying. washed. This pro- cedure results in a gamma between 0.95 and 1. 05, and a typical H and D curve, showing density as a function of exposure, is given in Figure 7. The curve is obtained from densitometer measurements on a test exposure of a gray scale, which provides some 21 discrete known exposures. The film may be processed in a dim medium-green dark-light; it is necessary to dark-adapt the eyes for about twenty minutes in order to see at all while the processing is done. It is possible to retain green-adaption, outside the dark-room, by wearing red goggles; these will be provided for the Observers who-may wish to watch the processing operation. Processing of test films, designed to check exposures and proper den sity of film-speed markers, will be carried out on Parry by these procedures. Lens-calibration films, and the shot films, will be processed in Berkeley together with gray-scale films to verify the sensitometric control. 16. Duplication of Films After the original negatives have been analyzed at Berkeley duplicate prints will be produced in Hollywood. The prints will contain portions of the reticle, so that scale factors will be maintained. In the printing process, the exposures will be adjusted to compensate, in part, for the widely vary- ing densities on the original and to preserve the greatest detail possible. Duplicates of the original reticle will be produced on glass plates, in order to minimize dimensional changes, for distribution to the Observers. 17. Time Signals The cameras and accessory control equipment will be placed in a cab at the top of a 300-ft tower, near the north end of Parry Island. (Figure 8). Operation of the photographic station is entirely automatic, requiring no operators at shot time. . The master sequence timer, located in the Control Building at the foot of the Parry tower, generates time signals for distribution to all experj e f° Nab PE (~ Q ay te ke t i. > menters in the area as well as those needed to ARM and FIRE the bomb. 4 € - 22 -