I have a 46559, Petzval Portrait type, with year of production written on front lens border as 09. I was told that this is 1909. Pictures in this thread: http://www.largeformatphotography.in...zval-lens-info
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I have a 46559, Petzval Portrait type, with year of production written on front lens border as 09. I was told that this is 1909. Pictures in this thread: http://www.largeformatphotography.in...zval-lens-info
It is surprising that so few have lost their edge markings! Most of the older lenses must have had their Balsam changed at least once. I have done over 10 balsam "operations" with pencil/ink marked lenses - they fade a little, but are still readable.Quote:
Originally Posted by Amedeus
But perhaps there are just focal lengths/stock numbers on the lens edge on yours?
I have updated with the new data and moved the probable start of date edge writing in post #20 as yours is the highest number without a date!
The 12,782 definitely has no markings, I don't own the lens but the seller has taken images of the glass and there's nothing there ... he's also very knowledgeable ...
The 12,651 is indeed mine and I still was not able to get the cell out of the rear. The rear either contains the front achromat or the positive of the rear cell only ... I don't see any balsam separation, so it could be the latter ... I will get it open though,
just have to move on to more aggressive methods as I would like to read whatever is left of the full text rather than reflected, upside down and obscured ... hahaha ...
EDIT:Quote:
Originally Posted by Steven Tribe
Got the now confirmed front cell open from serial 12,651, couldn't see any balsam separation as it was all nicely hidden behind the rim.
Lens reads "Hermagis à Paris" followed with the number 637-661. I determined the focal length of the achromat to be 379mm (14"15/16), no relation to either one of the numbers. I feel strongly though that given enough numbers collected from lenses we can crack this code also. As Steven and others have indicated, either lot numbers, focal length numbers, stock location parts etc.
Convertible Petzval engraved "Hermagis Opt. en Fab. nt - Brevere s.g.d.g - Paris". The serial number is 6872 many digits but nothing that makes up a date on the rim of the glass according to previous owner (lens just got sold).
In line with previous observations although it would be worthwhile to know what the digits are. There's a reason for them ;-)
Cheers,
Attachment 172257
Added to the #20 posting!
This is second earliest (confirmed) serial number!
There are quite a lot of serial numbers now and there are some conclusions:
Serial numbers on barrels/sleeves started at the same time that the Convertible was introduced. Production of ordinary Petzvals was virtually given up the first few years. The recorded 3xxx engraved number (P et P) is likely a misreading of 8xxx. The Franko-Prussian conflict is easily seen in the serial number and date gaps. Looks like about two years of no production.
The numbers written seem to represent different identification systems at different periods. They differ between lenses in the same Petzval. Some could be focal length, but others look more like stock reference numbers!
Added more info and detail in post #29, #33 and #34
Added info in post #30 of the owner of lens 12,782
My guess is that the numbers 637-661 on the front achromat (same as my lens that unfortunately lost its rear) possible relate to the focal lengths of the individual elements (thanks Tracy Storer) and the same for the rear elements keeping in mind that at one of them is negative.
Will need to run some math to verify if the above hypothesis is plausible in light of tolerances and measurements.
I've seen few Darlot lenses were the focal length of the group was mentioned in pencil on the edge.
EDIT
I've run the 637-661 and 696-469 numbers through some basic lens math and arrive a a total calculated focal length of 235mm with an assumed spacing of 100mm between front and rear group and a spacing of 4mm between the two elements of the rear group. Not totally impossible numbers in light of tolerances and my assumed boundary conditions. We'll need more of these numbers from other convertible petzvals to verify if there's merit to this hypothesis.
Cheers
In the hope of getting more early lens data, I have purchased another early no serial number plain Petzval. The announced size corresponds well to Hermagis size 9, which is the larger medaillon size.
I think I forgot to mention that the first no serial number I got with the lens hood insert deep washer stops, has a rather nice velvet seal. I wonder if the new one still has a similar?
I also asked in the other thread but have you measured the focal length of this lens ?Quote:
Originally Posted by lungovw
Thanks,
Well this "no serial number" arrived to-day, so I have had to change my plans for to-day. 18 hours from Austria to Denmark - obviously no Christmas rush yet!Quote:
Originally Posted by Steven Tribe
It is, as expected Hermagis size 9 Petzval for Medaillon and 9x12cm. The brasswork is, in everyway, identical to the other early no. 7 I have. The internal baffle has been removed and the light insulating blackened paper strip has been removed, but it is easy to see where it has been.
There are plenty of paired numbers on both the usual lenses and a double pair on the achromat. I think there is a good deal of "assembly" logic in writing actual focal lengths on lenses or combinations (Rear pairs). I am sure they could grind and polish accurately, they had to work with glass that must have had some variation in refractive index.
The numbers on photo 2 are from the rear pair, whilst the two sets on photos 3 and 4 are both from the Achromat.
The future project in "nailing the lens markings" could be a separate thread?