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Added to the list!
This size no.4 is popular! Both Rudi and I have it.
I have just realised that most french makers seem to have started using serial numbers during the middle and late 1850's. Will research a bit and find out if it is worth a separate thread, especialy as to who started the trend.
Do you know what's written in pencil on the edge of the lenses ?Quote:
Originally Posted by purplecloud
Just curious, part of the fun finding out ;-)
Cheers !
Received a #4 Hermagis Convertible 9787 today.
Front Achromat reads "Hermagis" and in similar cursive writing "B.L.N". In addition in what I believe to be a different style writing "E. Vallet"
Rear negative meniscus reads "Hermagis" and in similar cursive writing "B.L.N". We find the same "E. Vallet" writing. Almost illegible, in small cursive also E. Donche. Some rim glass damage to this element. Rear group had the elements flipped and the positive lens reversed. Corrected upon assembly.
No WHS but there was a thick black cardboard washer style restrictor installed marked in pencil with F=7 in a cavity made for the purpose. Need to remove the rear lens group to access.
No dates, no slew of numerals but possibly the initials of the workers and equally possible names of others who have worked on this lens. Achromat is flawless, no separation, so most likely well maintained during life.
EDIT
What I'm describing above as a washer style restrictor was of course used for aperture control on the landscape lens. This #4 has a lip to prevent the stop to fall through. My #3 convertible (1859) doesn't have this feature at the landscape side of the lens.
Cheers,
Hermagis Petzval (non-convertible) serial #15981 from 1874, focal length 215mm, WHS.
Added to the list. There are quite a few years in the 1870's after this one (1874), where we still have holes and, perhaps, low annual productions. Could this be due to Dallmeyer's Patent Petzval becoming popular?
Hermagis convertible, #7 size, serial number 9277j, no WHS
No markings on front achromat (was re-balsamed at least once in its lifetime)
Rear cell negative lens marked Hermagis, no other marks found. This lens had every single thread mis-treaded.
The restricter has provisions for removable stops.
This #7 design is slightly different than my other #7 design (serial 12561 with WHS)
I was stimulated to have a look at my no. 8 plain petzval again. This is one of my two pre-serial number lenses (and before the introduction of the convertible patent lens). Full of edge numbers - I think I have mentioned this before. I did some comparisons with the table of lens diameters and size reproduced in the P et P Hermagis booklet. This gives the diameters in both the original (archaic) measures as well as modern metric measure. This table cannot be very precise, as there is no constant factor for ligne/mm. This number 8 is listed as 19 lignes and "translated" to 44mm - whilst the real diameter is 41/42mm on my no. 8. I don't think this is an "early variant" size as Hermagis (And other makers) stuck to the lens diameters they had selected early in their history. Hermagis, used lens diameters 54, 61 and 81mm for all series until their anastigmatics.
Table of 19th century serial numbers is updated.
Hermagis Petzval lens with serial number 2163, focus length about 135mm.
Unfortunately, the making date was not marked on the glass.
Attachment 174021Attachment 174022Attachment 174023
Well this causes a lot of consternation!
The serial number looks original.
It looks like a plain Petzval which would match with the date deduced from the serial number (1853?). It makes the previous reported earliest number of 3xxx look more likely. Hermagis must have "ocassionally" added serial numbers on their lenses before serial number 6xxx. This must be the case as there are only 2 reported under 6xxx.
No lenses this early have date written on lens edges.
Perhaps you could look inside the barrel to see whether there is a black backing paper strip around the inserted geared track? Or signs that has been one there in the past - and unblacked brass section where the paper used to be?
And lens glass diameter is?
Agreed that this is somewhat of a assumption changer.
The lens clearly says "Brevet d'invention" ... question now is, which invention ? The 1856 ? That would be hard to believe as this would suggest an enormous output. What there another brevet/patent prior to 1856 ? Or was this simply bluff ?
Quote:
Originally Posted by Steven Tribe