ay Deo lg-nm Fastax coneras, incorporating actoamatic expeosere ccetrsl, vere used. These cameras, cperated at 2X0 frames ger second, Save a tila capacity of ~OO fence. re ia characteristic of approzisate:y 100 usec. this sechanisa to orlese acd folisn alrer The initial iiiter setcing fe made for aderuate exe posure S:rizng the firse 100 psec. Additional ta evaluation of the exposure contre] systea, resulticg fila recores sere interded to provice early-tise radi: versus-Ltize data as well as documeatazy coverage. 11.3.4 Mitchell Cameras . Three Mitchell 35-cam high-speed sction picture caseras were located at the camera staticn on Johnston Island. Anscochrese color fila was used. Gen- erally, eaphasis was cn radii versus time and later tice phenomena, in addition to qualitative or doc.mentary coverage. These caceras afforded a wide field of view fapproxicately 36 by 48 degrees). Foz che Crenge event, three off-site Mitchell 35-com morion picture cazeras were edded. Two caseras were located at French Frigate Shoals and one vas placed aboard the USS Boxer. scale phenocena. Prine interest was in very late-tizne, large- Here also, Anscochrese color fila was used. These cameras were inteoded to provide qualitative data only. 11.3.5 Ballistic Plate Cameras Two ballistic plate cameras, especially designed for obtaining positioa- ing data on 10+ by l2-icch sensitized glass plates were used. Four sets of fiducial carks were exposed on the plate for accurate and repeatable reference. Lens focal length on these cameras is 12 inches. To assure precise position- ing, the ballistic camera incorporates a sount for lccatisn of a theodolite directly over the nodal point of the lens. One casera vas located at the west end of Joimston Island and the second was established on Sand Island to obtain as long a base leg as po:sible. An explosive capping shutter was designed to close while the mechanical smtter was still in its ouch slower process of closing. Exploding che charge was acccoplisked by a photocell-controlled circuit triggered by the first light Qs ~~ & Effective closing time was approxizately 250 usec. SX) of the test detonation.