I recently bought the Voigtlander No.6 petzval sample.
Being a novice of old brass lenses, I looked up the info available on internet and would like to share the findings and thoughts, which may be obvious for some of you experienced guys.
Please bear with me for the long notes below….
More insights are very helpful, so give me feedback if any in the comments.
I found some related threads in this forum.
https://www.largeformatphotography.i...n-if-possible!
https://www.largeformatphotography.i...-but-which-one
I think the attached pic is the actinic focus shift scale mentioned in p74 of D’Agostini’s German 19th centry lens book. This Voigtlander No.6 petzval lens was made in 1857.
The 7 major increments measure 30.60mm.
Each major increment is lined 4 minor increments, each of which measures 1.092mm. Multiplying this by 2 equals 2.189mm, which is close to Line (Linie) 2.195mm by Viennese unit.
https://en.m.wikipedia.org/wiki/Obso...of_measurement
12 Lines(Linie) equals 1 Inch(Zoll) 26.34mm.
So 2x12=24 minor lines equal 6 major lines, I measured the 6 major line length by the vernier calipers, which indicated 26.31mm close to Viennese 1 inch, 26.36mm.
This evidence shows Voigtlander used Viennese standards for measurements in 1857 I suppose.
I cleaned the lens elements and noticed the rear group was flipped backwards, so I corrected to the original positions.
The serial number was marked on the side of one of the rear elemets, which means it’s the original.
The waterhouse slot design is a bit different from typical two ring sandwich design. It’s rather like a Lee filter holder design. According to the wiki below, the waterhouse slot invention was as early as 1856, which might say the sample serial production year 1857 with WHS.
https://en.m.wikipedia.org/wiki/Waterhouse_stop
The rack and pinion mount of the barrels was changed to the rigid mount by March 1863 based on the German catalogue attached and by some time of 1864 based on the description of the Negretti and Zambra catalogue.
If anyone has info about earlier Voigtlander catalogues than 1864, let me know.
The actinic focus shift was said to be eliminated from the serial No.7200 on May 28th, 1858, using a combination of glasses, the focus shift scale of this sample meaning it’s still actinic, verifying the serial number 6855 predates that change.
The German catalogue of May 1863 states the older models with the chemical focus shift can be changed none by changing the rear achromatic lens. This modification can be made above No.3600. The samples with the lower number must change both front and rear lens groups.
The German catalog states No.6 focal length is 14” in Viennese inch,
14 × 2.63 = 36.82cm in the German catalogue
14 + 5 ÷ 8 = 14.625 in N&Z
14.625 × 2.54 = 37.15cm
The difference is 37.15-36.82=0.33cm
That is quite close, so N&Z originates from this catalogue. But 14+4/8=14.5 inch in English unit 36.83cm is rather close to 36.82cm.
The German catalogue in 1863 states at the title, New construction without chemical focus.
At first, I thought this sample doesn’t really match to the No.6 described in either German or N&Z catalogue. It’s older than no focus shift models. Voigtlander changed the design when she redesigned the series at the time of no chemical focus shift, but no change in focal length, lens diameters were made by comparison between the 1857 and 1863 catalogs for No.6.
The sample front element diameter measures 112mm, the rear 114mm.
The German catalogue states
Oeffnung in old German? meaning Offnung? in current German?, opening diameter or aperture diameter of the lens casket hole, not the actual size of the lens itself.
The English catalogs apparently misinterpreted the opening diameters as lens element diameters??
48”’ × 2.195 = 105.36mm front element group
50”’ × 2.195 = 109.75mm rear element group
where triple quotations “‘ mean Linie in Viennese unit.
The corresponding measurements in N&Z 4” 3/16, 4” 1/4, which convert to 110mm, 112mm in Viennese unit, 106mm, 108mm in English unit. So N&Z’s element units are in English unit inch, based on the German catalogue conversions to mm scales.
By referring both of the diameters in both units, neither of the catalogue match this sample element diameters.
By measuring both front and rear openings of the lens caskets, I confirmed the 48”’ and 50”’ refer to those openings indeed.
So would be for N&Z.
The N&Z catalogue says the No.6 focal length is 14” 5/8, 371mm by English inch conversion, 385mm by Viennese conversion.
Later I found the German 1857 catalogue.
https://archive.org/details/vademecu...nder+zoll+lens
This edition is mentioned about chemical focus shift and older models can be changed to none chemical focus shift, but the main list and the title seems to say focus shift lenses still in stock at those times compared to the 1863 German catalogue. The 1857 catalogue explains how good Voigtlander focus shift lenses are and in fact focus shift lenses are better in performance than non focus shift lenses other makers made, but in the end of the paragraph, it’s stated that Voigtlander now makes non focus shift lenses.
1855 and 1856 catalogs in English don’t mention about focus shift.
https://archive.org/details/1855Phot...age/4/mode/2up
https://archive.org/details/1856Phot...e/n77/mode/2up
1856 English catalogue explains the availability of rack and pinion in No.6 as an option, which the original owner ordered it so.
1857 german catalogue also states
the No.6 with rack and pinion option, but not mentioned anymore in 1863 German catalogue.
These facts support my sample had the rack and pinion option at the production.
But no mention is made for waterhouse stop as “central-blenden” as in 1863 German catalogue for Voigtlander pages but aperture slits are mentioned already.
It seems that there were no dimentional change in terms of lens diameters, focal length and barrel size before and after the no focus shift redesign.
This No.6 is I suppose the predecessor of the 7B quick worker, Schnellarbeiter.
7B sample in 1880 has the Dallmeyer layout already.
So B series already had that layout before the 1885 change below.
Note: just not to be confused with the use of the “6” nomenclature of the Voigtlander petzval history,
The 6B of the quick worker series seems to appear circa 1878 with the focal length 12”.
The No.6 engraved 6 on the barrel has 12” 306mm focal length.
The numbering of 6 and 6B with 12” focal length is passed on to Portrait Objectiv I No.6 12”.
Early 6 without any engraving = 14”
Late 6 with engraving 6 or 6B or Portrait Objectiv I 6 = 12”
Early 7 without any engraving = 18”
Late 7 with engraving 7 or Portrait Objectiv I 7 = 16”
Late engraving 7B = 14”
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