Emil Busch Petzval generation transition history: sampling needed to testify & modify

[mhayashi]

I am going to receive a new flavor of Emil Busch petzvals from Finland soon.
As I don't have this brand, I started to study Emil Busch petzvals since yesterday.

Here is the old thread relevent to this topic.
https://www.largeformatphotography.i...zval-Lens-Info

In this thread, the scope of focus is limited only to Emil Busch petzvals.

I collected the relevent Emil Busch catalogs and calculated FL and F-numbers based on the front and rear lens element opening diameters.
WHS necking in the barrel is ignored as the convention and convenience purpose for identification of samples.

I assume all units of the older catalogs are in
Preussian 1 Zoll = 26.15mm
Preussian 1 Linien = 2.179mm

Attached is the tentative pdf I made which shall be updated with new findings as usual.

I have already searched engraving images of Emil Busch petzval samples, but no corresponding info about serial numbers.
I want you guys to post samples with the front and rear lens element opening diameters, the optical layout, the serial numbers and any engravings on the barrel.
I shall match the samples to the table and where it fits in the column and row to testify and modify the table accordingly,
speculating the serial number bands, periods and so on given the generation period row in the table.

I have put some engraving patterns on late models but no serial numbers for the future research.

Thanks in advance for your help.

April 9th, 2024
It turns out that Back Focus focal length descritions are updated before 1875 catalogs.
BF+1/3*BF=FL is applied to the calculations for FL before 1875 catalogs,
as this 1/3 factors are derived and consistent having both BF's and FL's described in the 1875 catalog.

After 1875, the focal length descriptions are in cm, but the numbers are in BF based on the context in accordance with the previous catalogs to match the FL, given the following catalogs.

1880 Handbuch_der_practischen_Photographie,
1884 1893 1899 Ausführliches_Handbuch_der_Photographie

After these catalogs, the focal lengths are described as FL, not BF, as in the following catalogs.
1904 1909 Emil Busch catalog (UK in inches)
1912 BUSCH PROJECTION AND, ENLARGING LENSES (UK in inches)

EmilBuschNomenclature20240520.pdf