Recent content by physixvox

Not exactly correct. The 7 inch f/2.5 was for aerial 4.5 inch roll film format, nominally, and the 12 inch f/2.5 is for 9x9 inch roll film. I have a couple of these 7 and 12 inches, one of the 7 with the original 4.5x4.5 camera including the roll film cartridge still on it. See USAF lens data...

The way these f/2.5 Aero Ektars were used originally is for night recon photography, partly using flash bombs. You often find 12 inch 2.5 Aero Ektars inside Fairchild "Night Photo Shutters". So the limitation to overcome here was to make a Double Gauss to be as fast as possible so you could get...

The Epis series, like most episcope lenses, is a Cooke triplet design. Usually in these (like also the TTH Cooke Series II), the aperture is positioned close to the negative center element, on its rear side. That's also true in descendents of the triplet design which have doublets for the front...