Hi,
is there any data concerning Derogy lenses's serial number or date of manufactured?
Around which year, the etched crown start to appears on the barrel of the lens?
Hi,
is there any data concerning Derogy lenses's serial number or date of manufactured?
Around which year, the etched crown start to appears on the barrel of the lens?
Yes.
I'll get back to you, am busy with re-doing an achromat's balsam.
The date will have to be by deduction.
The first Derogy's didn't have numbers.Then they did - but I don't think they started from 0001!
I enclose some engraving types and the earliest number I can find with a serial number and the crown. I think the "Paris et Londres" was introduced at the same time perhaps out of respect for Queen Victoria!
The one illustrated is a RR so it must be from around 1870 at the earliest.
So compare your serial number with this one.
Corrado's book has much better quality photos.
Thanks Steven!
I read the book and there is not much about them concerning date even in the lens's vade mecum. Mine is 13xxx, so i figured it might be after 1870 from what you're writing.
Is it a RR - like the one shown?
To be honest, I doubt whether Derogy would have imported this into the UK until the Dallmeyer Patent had expired.
No, it is a bayonet type petzval.
I found the Derogy importer for the period 1860-65 (Chapman Lloyd). They may have started their own office in London after this time. But I think that the mostly likely date is 1880.
Thanks!
That will give me a good idea...
The idea that the crown was added to the serial number sometime between a period 12,000-13,000 has been rather destroyed by a 5*** serial number with crown! So perhaps the sequence given by Corrado is just a co-incidence and the crown engraving was the start of a whole new serial number sequence?
This is not correct (The idea of a new serial number series) and I was tempted to edit the comment!
There is now a great deal of information available in Pont et Princelle's booklet (no. 16). The date of the patent (Foyers multiples 1858) means that 4,000 is around 1858.
Bookmarks