identifying old goertz lens

[dan_dozer1]

I have what I believe is an old Goertz Lens for large format work and

would appreciate information anyone could provide. I have looked in

Vade Mecum and there is a short paragraph describing the series III

lenses that were made in 1900. However, this paragraph describes the

series III as F6.8. It does not have the Goertz name on it, but is

inscribed Dopple Anastigmat D.P.R. No. 74437 series III/2 180 mm No.

107523. The somewhat confusing thing is the aperature scale starts

at 4.6 and goes 6/12/24/48/96/192/384. Is this what I've heard is

the "other F-stop scale" that was sometimes used with the old lenses.

I'm totally unfamiliar with this so if it is, how does this scale

relate to the conventional scale most lenses have? The lens is a

brass barrel with black paint on all of it about 2 1/4" across and is

mounted to an aluminum mounting plate that is about 3 1/2" in

diameter. I have not been able to remove the lens from the mounting

plate. The lens is in very good optical condition so I would like to

use it, however, I don't really know how it would best be used and

what character flaws (or good points) it might have.

 

Can anyone help me with this?

 

Thanks,

 

Dan Dozer

[User_503771]

Sounds like you have a lens with a European version of the old "US" stops. If I recall correctly, that stands for "Uniform System". But that system had f/16 as one of its stops, and that stop would be equivalent of current f/16. They doubled or halved the numbers apparently to represent the fact that each stop doubles or halves the amount of light coming through.

 

This lens most likely has one f-stop number that would correspond with some other system's. If 4.6 is wide open, then that f-stop would probably be 12. The European system was based around a different starting number, and the progression of numbers that I recall included f/12.5, 18, 25, 36, etc.

 

From what data I've got, your serial number would have fallen around 1902-1903. But I'm not sure if the serial number data I have applies to all Goerz lenses, both American and German, or just American.

 

I just took a look at an old 10-3/4" f/6.8 Dagor in a brass barrel from about 1910 or so. It's engraved with US stops and regular current-version stops as well. But the US stops are the ones calibrated around f/16. Wide open at f/6.8, the US stop equivalent on this one is f/2.9

 

Could it be that you have one of the f/7.7 Dagors? I can't remember if the Series IIIs started out early on as 7.7, or if they all were 6.8.

 

Anyway, if it's a Dagor, it'll cover 8x10 stopped down.

 

Could you post a picture or two of it?

 

Hope this helps.

[ole_tjugen]

First of all, if it doesn't have the Goertz name on it it's probably not a Goertz. The Dagor patent expired sometime before 1910, after which time just about everyone made "Doppel Anastigmats".

 

Since the type is in German ("Doppel"), it is probably made in Germany. That limits it to bout 50 different makers... I can't find any mention of a "Serie III/2" anywhere, most of them were called Serie III after the original Dagor.

 

Most DA's were f:6.8 to 7.7 depending on focal length - yours is probbly f:6.8. The aperture scale is probably in "Stoltze", given the age and origin. Stoltze numbers begin with 1 = f:3.16, and double for each step. If I've calculated this correctly, Stoltze number 4.6 is very close to f:6.8! Stoltze #6 can be taken as f:8 (close-ish), and just use the steps from there.

 

There were also another German system - Rudolph - Stoltze 1 is Rudolph 256 and vice versa - , a french system based on f:10, the US system, and some used the diameter of the aperture in mm or in/16...

[tracy_storer1]

I wonder if it says "C.P. Goerz" somewhere on it that you've missed. Goerz did

number their lenses, and a "Series III/number 2" IS a 7" lens. Your barell

seems to be marked in the "Goerz" system. (see table)

[dan_fromm2]

Your lens is an early Goertz Dagor.

 

If you'd searched in the Vade Mecum for the patent number, you'd have found: "Goerz was open to a visit by Emil von Hoegh who described his new double anastigmat and it was made, approved and a patent obtained. (No74437, 20/12/1892 or 1893). The patent ran out in 1909, according to Frerk. Initially it was f7.7, but Eder says Von Hoegh later increased it to f6.8."

 

Cheers,

 

Dan

[c_p_goerz]

Here is a handy table you may find useful...

 

<img src=http://home.earthlink.net/~dagor77/fstopscale.jpg>

[dan_dozer1]

Thanks everyone for all your help. With the charts that Tracy and Dan provided, it appears that my lens is the F6.8 series III that is indicated in Vade Mecum. The numbers in the Stolze and Goerz columns seem to coincide with the standard F-stop numbers making the lens from F6.8 to F64. Here is a rough photo of the lens for those who are interested (hope the photo works).

[User_503771]

Ah!

 

"D.P.R. No. 74437" -- maybe "Deutsches" and then their words for "Patent Register"?

 

The lens photo worked fine. Is the retaining ring small enough to fit on a lens board for your camera?

[dan_fromm1]

Dan, thanks for the credit, but I don't deserve it.

 

That very useful table of aperture scales was posted by "C P Goertz." The person who posts here as "C P Goertz" sells photographic equipment, and sometimes other things too, on eBay as dagor77. He's explained before that he doesn't post here as dagor77 because he doesn't want to be seen as being helpful for, um, business purposes.

 

Cheers,

 

Dan

[uli_mayer]

To Michael and Dan,

I am pretty sure it does not read "D.P.R" but "D.R.P" which is the official abbreviation for "Deutsches Reichspatent". Uli