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There have been some additions to the list (post #68) in the last few months.
Nothing that adds to our “cumulative knowledge and guesswork”, but also nothing that contradicts start of serial numbers and pencil dating either!
9293 is a no. 5 convertible which does have pinion track on both halves of the split barrel - unlike the no.6 mentioned in post #120.
I have added another pre-serial number small Petzval to the list on post #68. I have called it VVVV. It is the same size as YYYY.
It would be fantastic IF the mystery numbers were the same on corresponding lenses!
UnfortunateLy, they don’t match - but they have an obvious relation to each other.
YYYY has 209 - 44 on the achromat and 346 - 17 on the rear cell.
VVVV has 346 - 45 on the achromat and 343 - 18 on the rear cell.
I can’t see an obvious link apart from the 44/45 and 17/18. And the first number cannot be a lot number (346/346) - unless, of course,both lenses were stored (perhaps paired) at location 346.
I have made some changes in summary serial no. list in post #68 and removed content of #20 so there is only one list available.
The, new to me, Medallion Petzval VVVV has a unique internal washer stop system. The internal barrel has a screw thread which also functions as a mounting screw ring for the two lenses and metal spacer in the rear cell
A new clue has turned up about the meaning of the edge lens numbers. I have received 11290 today and the unusually fresh number on the rear lens shows (apart from the Hermagis a Paris) “696 Bleu”.
I can’t think of any logical explanation for the use of blue - other than identifying a specific physical location in a lens storage facility?
This lens also has a good example of the use of blackened paper to stop the inevitable light leaks around the track set into the barrel. The area showing where the original paper was is obvious and the quantity of edge light leaks from one of the track sides is quite substantial. The papers (two pieces) were glued in after the baffle had been installed, but before the barrel interior had been blackened
Another pre-serial number small Petzval!
Unfortunately, a bit battered because of an impatient previous owner with inappropriate tools.
This is a second example of an internal stop system which attaches to the rear cell.
This has what we usually call assembley identification roman numerals -I II III IV V etc. The threads which (in the era of hand cut threads) meshed easiest were marked with an identical Roman numeral.
The extreme high marking numbers of the two (16/XVI and 28/XXVIII) perhaps suggest that there may be some sort of batch numbering/identification as well.
Photo 1 Hermagis Petzval rear cell - both types with/without internal disc stops.
Photo 2 Both examples of internal disc stops.
I found this thread when searching for information on a Hermagis lens I acquired recently, so I'll post the details to add to the database. The lens is an Extra Rapid Special no. 4, serial number 40717. Pencil edge inscriptions - front element "Hermagis Opticien a Paris E.R No.4 (129-186-05)", rear element "ER No 4 (129-505-05) Hermagis a Paris"
I'd sort of expected it to be a Petzval design, but it appears to be a triplet - I can't see any evidence of cementing on the front element. I got the lens with some damage and partly dis-assembled, if I've put it together correctly the focal length is about 96mm assuming the slot for the Waterhouse stops is somewhere near the nodal point. Rear focus distance is about 68mm.
I think this is a large lens (lens diameter 8cm or 8.6cm) which doesn’t match the focal length of 96mm!
There is only one ER no. 4 around in the 1900/1910 period and this is in the table below. Note that Hermagis used the reverse sizing scale - 1 is the largest lens and 10 is the smallest.
I would guess that there is a problem with the mix of lenses you have! If you have 4 separate Lenses, then 2 of the lenses are probably the two halves of the front achromat which has cleaned and now ready for reglueing! I have seen a couple of lenses were this has been the case.
If there are only 3 lenses - and none are an achromat- then you don’t have the complete optical set for the no. 4 Petzval, unfortunately.
I've re-examined the front element and there is evidence of a cement line, so it's likely to be an achromat. Very faint, missed it first time round, I was more focussed on sorting out the rear elements and removing the dent from the rear of the barrel.
However it's a small lens. The diameter is 44mm - which would make it a number 10 according to the table. I'll try and get some pictures tomorrow.
The no. 10 was very popular and was used on early sliding box cameras. I have 3 of these 44mm Petzvals - but these are the convertible and plain Petzval versions - not the ER a type you have.
You can compare the front achromat from serial number 10,376 with yours! Note that the first number is next to yours. This supports the idea that the numbers refer to physical stock locations of finished lenses. Yes, this one does have edge balsam decay!
I did expect some balsam decay, but as my lens is only 118 years old then it's a youngster :-) Looking at your numbers, is the first digit a 1 or an open bracket? (the preceding inscription isn't visible).
Photos attached. The lens is the front achromat.
Attachment 242008 Attachment 242006 Attachment 242007 Attachment 242009
Yes, the first mark is a bracket.
The 05 within the bracket is the year of assembly - 1905. And mine is from 1883.