[. . . ] This makes the lens suitable for scientific requirements such as measuring the zenith or azimuth angles of astronomical bodies or recording cloud distribution patterns in the sky. It is also useful in surveying work which requires checking the camera position. [. . . ] ^ " - - - ^ ^ ^ Screen Camera ^ " " " " - - - - ^ ^ A/L B C D E G1 G2 G3 G4 HI H2 H3 H4 J K/P M R A A T F3 F2 © © ® © © © © © © © ® -a © © © © © © © © © © © © • When the Teleconverter TC-200 is attached to this lens, use the following table: ^ " ~ ~ ~ - \ ^ ^ Screen Camera -^^ A/L B F3 F2 • © ® © -Vz O * Excellent focusing ®= Acceptable focusing The image is brilliant from edge to edge, but the central rangefinder, microprism or cross-hair area is dim. A= Acceptable focusing The in-focus image in the central spot may prove to be slightly out of focus on film. Q= Exposure measurement not possible; lens/screen combination permits only focusing operation. , — y2) in the tables above mean that the film speed (ASA/ISO) should be set against the proper compensating mark as shown in the diagram below. When no exposure correction is indicated, the film speed (ASA/ISO) in use should be opposite the • index. C D o o o o E G1 G2 G3 G4 HI H2 H3 H4 J K/P M R T © © O O © ® © ® ® o o COMPOSITION Using a fisheye lens requires much more thought and planning about picture composition than does a conventional lens. The lens not only produces wideangle distortion but also exaggerates the relative size of objects to conform to its circular format. Objects near the center appear larger than those at the edges, and they show less optical distortion. The entire field is pushed into the distance and spatial relations are transformed. and a slight shift in camera position produces a whole new set of distortions. 12 Be careful not to include in the picture unwanted objects such as the legs of a tripod or the hands or feet of the photographer. 8 has three other tripod sockets on the back so that the camera may be mounted on a tripod facing upward. [. . . ] For example, a point j n the image 4mm from the center represents an object at an angle of 37. The table below gives zenith angles for points at given distances from the center of the film image. [. . . ]