Originally Posted by
Steven Tribe
We are lucky (or, perhaps unlucky!) in that Derogy had a whole range of different engravings!
Perhaps these represent different dates, but perhaps not. There is certainly a range of English language engravings - including the UK crown symbol (Harry and Meghan!) and V R ( Victoria Regina). Perhaps we will get some idea of whether there is a obvious date (serial number) link with the actual engraving type.
using my own small collection/D’Agostini/Pont, I can see the following variations
French / English market. ( V R, “Crown”, Patent)
Opiciens/Optn/Fabt.
PARIS/Paris/a Paris/Paris & Londres/Paris Londres
Brevet d’Invention - used only with Objectif foyers multiples (“patent” on English versions)
Brevete - probably only used on Aplanats
Engraving on the “additional lenses” of the Foyers Multiples. These can be in the face or the sides of the loose lenses (see attached photo)
Will add to this list of different varieties of engraving as other variations are identified.
Eventually we will have a check list for (nearly) all Derogys.