11.3.6 Timing Reference One-bindred-cycle time saarks were placed on filo records in the Mitchell ca=eras and cne-thousani-cycle Cining was supplied to all other high-speed Cameras and the spectrogragh ip the Jodostoo islam) camera station. A sispie Cine sack generator was used with the Mitchell casera (slow-speed) aboard che USS Boxer. It provided one tive sark approximately every 7 seconds. This Caoera was used during the Orange event only. Syne marks were placed oa all fila records in the Fastax cameras during the Teak and Orange events. These were supplied through Cwo sync sark genera- tors, each triggered by a photocell which was acruated by che first light of the detonation. During calibrarion of these generators, a delay of approxi- mately 60 psec was experienced between the first visible light from an electronic flash lamp and actual lighting of the séon flow Le=p. 11.3.7 Filters Metal interference filters were used for the narrow-band pass filters. These were generally second-order filters characterizad by a width of half- peak of 100 A and a base width of 1000 A. With the 5000 A and 6500 & filters it was necessary to use kratten gelatin filters to suppress unwanted bands. Figure 11.2 shows transmission curves of the narrow-band pass filters combined with the Wratten filters where the combinarion was used. These curves are measured with approximately the same angular spread (5 degrees} in che light az was present in the field. The so-called neutral density filters (Wratren No. 96) were calibrated at the wavelength used. Tabies 11.1 and 11.2 give this effective neutral density for the filters used. 11.3.8 Fila Recording The quantitative ceasuresent of light intensity using photographic emulsion requires establistment of known relationships berseen exposure and resulting density produced in the developed equlsion. The reader is referred to accepted sources such as nee sl? or Jones} for a more complete discussion of the general problem. A thorough discussion of fila acd camera calibration techniques and data reduction methods for this project is given in a report by Palser.1*