View Full Version : construction of 14" Blue Dot Trigor

John Schneider
28-Apr-2007, 17:45
I just received a 14" BDT and was doing some research on it (see http://www.largeformatphotography.info/forum/showthread.php?t=14330&page=5&highlight=7x17+lenses for some background). There was some discussion in this thread about whether it was a Dagor construction (6/2) or if it had additional elements added (which I assume would make it like a Reichert Combinar 8/2 construction).

While this doesn't prove anything, I found an interesting entry in Henney and Dudley, Handbook of Photography, 1939. In addition to the Series 3 Dagor (f6.8, 70-90 degrees of field, f. l. 40-900mm, 6/2 construction) there is listed a Series 4 Dagor (f11, 90 degrees of field, f. l. 300-1200mm, 6/2 construction). Any chance this might be the predecessor of the Trigor?

Neil Purling
29-Apr-2007, 13:39
The Trigor is a process Dagor, optimised for 1:1. The old figures for dagor coverage..Hmm. Say 70 degrees for your lens, maybe a bit less if used at infinity.