Originally Posted by
Kerry L. Thalmann
A Goerz brochure titled "The Lens for the Graphic Arts - Goerz Red Dot Artar" lists the coverage as 46 degrees for all focal lengths (from 4" to 70"). There is also a table that lists the film formats covered at various magnification ratios. For the longer focal lengths, the listed formats at 1:1 are:
30" (762mm) - 30"x40" (127cm format diagonal, 129cm IC at 1:1 and 46 degrees)
35" (889mm) - 36"x45" (146cm format diagonal, 151cm IC at 1:1 and 46 degrees)
42" (1067mm) - 48"x56" (187cm format diagonal, 181cm IC at 1:1 and 46 degrees)
47.5" (1207mm) - 48"x64" (203cm format diagonal, 205cm IC at 1:1 and 46 degrees)
70" (1778mm) - 72"x80" (273cm format diagonal, 302cm IC at 1:1 and 46 degrees)
The last two sets of numbers in parentheses are the calculated format diagonal and image circles at 1:1 based on the stated 46 degrees of coverage.
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