180mm Dagor Coveragegreenspun.com : LUSENET : Large format photography : One Thread
Didn't see this in the archives or in Google search. Does anyone know the coverage of a Goerz Dagor f7.7 180mm lens? Just purchased one and will primarily use on a 4x5, but is there any chance of it covering 8x10 stopped down? Thanks.
-- Donald Brewster (firstname.lastname@example.org), November 05, 2001
I just sold a f6.8, 7 inch, Goerz American Optical Company Dagor that I had for a number of years. While I don't have documented image circles, this lens had coverage similar to a standard 180mm plasmat lens. (e.g. Symmar-S.) Assuming that image circle for a design of lens is proportional to focal length, the published image circle of a 150mm f6.8 Gold Dot Dagor is 210 at f22, implying that the image circle of a 7 inch f6.8 Dagor at f22 is 250mm.
Based on my experience, the 180mm lens will not cover 8x10, even stopped down. The published image circle for a wide angle 165mm Dagor is 289mm, and that even this lens will cover 8x10 only when stopped down to f32. I have heard that the f7.7's have a somewhat larger image circle than the f6.8's. Still, it doesn't seem like this would be enough extra image circle to cover 8x10.
-- neil poulsen (email@example.com), November 05, 2001.
I have a copy of an old Goerz Dagor coverage chart with data for 7" f6.8, 87degrees at f45 covering 8x10. only 5x7 wide open. Good luck, Tracy Storer, Polaroid 20x24 San Francis
-- Tracy Storer (firstname.lastname@example.org), November 08, 2001.