Is this a Dagor?

[Ole Tjugen]

Hugo - the Protar V was not a convertible, so the lens cells were always matched and carried the same serial number. The (German, 1909 to 1913) Series IV and (always) series VII were convertibles, and every single cell got its own serial number.*

The Zeiss Dagors were made after the merger. Before that, Zeiss and Goerz were competitors with similar and competing products!

*Caveat: Pre-1909 Series IV was an f:12.5 wide-angle lens, and that type stayed in production with B&L for a long time after Zeiss Jena started "reusing" the name for the 3-element convertible f:6.8 to f:7.7 Dagor-type lens. That lens never really caught on, and production seems to have stopped around 1913...

[Hugo Zhang]

Ole,

Is it possible that there was a period of cooperation/cross licensing between these two competitors before the final merge? It didn't work out of course and Goerz was bought by Zeiss. And this lense was a product of that brief period.

[Paul Fitzgerald]

Hugo,

that is an old Goerz 'Sector' shutter from the picture and they did open shop in New York but I don't think they ever produced 'Zeiss patent' lenses. B&L did produce 'Zeiss patent' lenses and were also in New York at that time

Oli,

"And then there's the "In." focal length. That was definitely never used in Germany!"

oops, Voigtlander & Sohn did on their Heliars way back when. I do have a #6 14 inch F:4.5 Heliar from Braunschweig, #112640 (7 Sept, 1911) and it's New York twin #65338. Yes, I'm nuts, I also have a 36cm version.

[Ole Tjugen]

"And then there's the "In." focal length. That was definitely never used in Germany!"

oops, Voigtlander & Sohn did on their Heliars way back when. I do have a #6 14 inch F:4.5 Heliar from Braunschweig, #112640 (7 Sept, 1911) and it's New York twin #65338. Yes, I'm nuts, I also have a 36cm version.

Eh yes. Voigtländer made some lenses for export with focal lengths in the "appropriate" units. Zeiss and Goerz seem to have preferred licensed production.

Yes you're nuts. But you're in good company - I have 120, 150, 240 and 360mm Heliars.

[Uli Mayer]

Like Ole, I'd rule out a Zeiss Dagor-type lens; the patent for the Doppel-Amatar was granted in 1908, and this lens looks older.
I'd also rule out that the lens was made after 1900, because in this year Zeiss started to brand its anastigmats "Protar" ( and some if not all licencees followed doing so).
I think we can also exclude that the lens was made by Zeiss itself, since the engraving doesn't say "Jena", and I doubt that Zeiss would have used "inches" especially for lenses that were to be sold on non-continental (European) markets.
If one accepts these assumptions we could delimit the lens' date to between 1900 and 1889/90, the year Zeiss started making photographic objectives, and that it was manufactured by a licencee, most likely by Ross (London) or Bausch & Lomb, the latter being Zeiss' sole licencee in the U.S. after 1892.
I take it for granted that it's an anastigmat. And a very early one because it's not specified to which series it belongs. The original Zeiss Anastigmats "Serie I" and "Serie II" with 5 lenses in 2 groups go back to 1892 and were made in f.l.up to 416mm (590mm); "Serie IIa was introduced in in 1893 ( also a 5-2) max. f.l. 433mm; "Serie III", a 4-2 design > 586mm started in 1890; "Serie IIIa" (5-2) >820mm in 1892; "Serie IV" ( 4-2) > 801mm; "Serie V" (4-2) in 1890; "Serie VI" (5-3) >410mm in 1891; "Serie VII" and "VIIa" (4-1) plus "Anastigmat-Satzlinse" from 1893 on.
A lot of choices!

But in addition there is/was also an "Anastigmatlinse" of 3 lenses in 1 group made by Zeiss in 1892 !! which had F 1:14.5 and was offered in 14 different focal lengths between 183mm and 1083mm. Maybe those two cells belong to this type.

(all data taken from Harmut Thiele "Deutsche Photooptik von A - Z", Munich 2007)

[Ole Tjugen]

That's great information, Uli!

I believe that last 3-1 "Anastigmatlinse" is the one for which Zeiss Jena "recycled" the Serie IV designation around 1910, with single cells from 15 to 70cm focal lengths. But Hans Schmidt "Photographisches hilfsbuch für ernste Arbeit", Berlin 1910, says

Es gelang der Firma vor kurzem die in den Doppelprotaren Serie VII vorhandene Bildqualität schon mit drei verkitteten Linsen zu erreichen. Dieser Typus kommt in nachstehender Serie IV auf den Markt und ist natürlich billiger.

I take this to mean that the 3-1 Protar was introduced no earlier than 1909, and thus would only have been sold with the "Protar" name.
And at the same time, B&L continued making the old Serie IV f:12.5; at least this is the only "Serie IV" I've seen - no Doppelprotars.

[Uli Mayer]

For further research I recommend to consult the Zeiss Archive. A starting point may be this:
http://www.archive.zeiss.de/hzeig.FA...%2300000C88%23

[Uli Mayer]

Here is in an illustration and a detailed description of the "Serie VI" Zeiss Anastigmatlinse (1893). Three lenses cemented together.
http://www.archive.zeiss.de/hyper.FA...t-Satzlinse%20

[Ole Tjugen]

And here's the f:12.5 Protarsatz Serie IV, 1908: http://www.archive.zeiss.de/hzeig.FA...A+IV%2C+1908++

It's not supposed to be easy...

[Uli Mayer]

There is no Serie VI 419mm ( = 16 1/2" ) Anastigmat-Satzlinse in the Zeiss list; but this focal lenght is halfway between size 4 ( 385mm) whose largest lens diameter was 31mm, and size 5 (450mm) with a largest lens diameter of 36mm. Thus, if the actual lens has a max.dia of ca. 33 to 34 mm I still wouldn't exclude that it is of this type.
It's all guess-work, I know.