View Full Version : 180mm Dagor Coverage

Donald Brewster
5-Nov-2001, 12:19
Didn't see this in the archives or in Google search. Does anyone know the cover age 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.

neil poulsen
5-Nov-2001, 20:20
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.

Tracy Storer
8-Nov-2001, 16:59
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