Quote Originally Posted by Oren Grad View Post
While we wait for the Dagor experts to arrive, here's a hint: older. Much older.
Depending on when and how they were manufactured Dagors of the same focal length vary quite a bit in coverage. I have seen 14" and 16.5" Dagors that would not cover 12X20, but I once owned a very old one that threw a circle of illumination large enough for 12X20, but of course I had to stop down to f/64 to get decent performance on the corners, and even that was not all that good. The serial number of the 12" Dagor that I had that covered 12X20 suggested that it was made in the 1920s so Oren is right in that you should think older rather than newer.

Sandy King