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View Full Version : Goerz Dagor speed mismatch - fake or rare?



Moogie
11-Feb-2018, 09:53
Hi forum friends,

I recently purchased a Goerz Dagor 270mm in the bay.

Now after arrival I am bit confused about 1 issue.
On the aperture ring it says f4.6 but on the inner ring showing the name, details and so on about the lens it shows f6.8.
So now I am confused if this might be a fake and just somebody added the inner ring to make it more valuable?
Nowhere on the lens, except this ring is any indication about the manufacturer.
On the other hand the lens seems to be of very high quality and the seller explained that this just might be a mistake of the production but that he is 100% sure this is an original.

What do you think?

174598
174599
174600
174601

Tracy Storer
11-Feb-2018, 10:00
It's very possible the barrel is marked in some other system of aperture measurement. I had a 10.75" Dagor that was marked in US (universal System) stops. The barrel looks like a Goerz barrel. If you lis the stops as marked, we can tell you what system the markings are and what the related "f stops" are.

mdarnton
11-Feb-2018, 10:01
First guess would be that someone took the cells and put them in a new mount from another lens to replace one that was damaged. One sees this quite a bit on Ebay with shutters that obviously are replacements, with the wrong f-scale.

edit: OK, magnifying one of the photos, I think I agree with Tracy. It looks like the numbers double, which would be some other system.

There's a table here, and a discussion:
http://throughavintagelens.com/2010/01/the-u-s-f-stop-system/

Dan Fromm
11-Feb-2018, 10:09
Look up Stölze scale.

mdarnton
11-Feb-2018, 10:24
I'm not bad at google, but I find nothing. How about some real help?

Louis Pacilla
11-Feb-2018, 10:37
I'm not bad at google, but I find nothing. How about some real help?

I just Googled F stops & got this table which I already had a screen shot of. https://en.wikipedia.org/wiki/F-number If you scroll down half way on this page you will find the Comparative Table Of Diaphragm Numbers

I believe this is the Goerz iris stop #'s as it matches up well w/ f stop readings as f 6.8 is just about right on the Goerz stops. Goerz # 4.5-6 = f stop 6.8

William Whitaker
11-Feb-2018, 10:48
Looks like an early Dagor. I had a 12-inch that looked exactly like that. Was marked "Doppel-Anastigmat" or "Dopp-Anastigmat" as I believe yours is. (But it's difficult to tell from the photo.

Dan Fromm
11-Feb-2018, 11:38
I'm not bad at google, but I find nothing. How about some real help?

<obscenities deleted>

I've just added a spreadsheet with the scales and formulas behind them to the list. If you need help finding the list, try the stickies in the lens section.

Louis Pacilla
11-Feb-2018, 13:04
<obscenities deleted>

I've just added a spreadsheet with the scales and formulas behind them to the list. If you need help finding the list, try the stickies in the lens section.

Brother Dan do you mean you put together a spreadsheet w/ explanations for the Comparative Table Of Diaphragm Numbers I posted in post #6

Steven Tribe
11-Feb-2018, 13:37
This is quite a common alternative F scale around 1900. The selection of the scale used was based on the market to which it was being exported to.

Suter followed Goerz as shown below in a 400mm Anastigmatic from the same period - this is a F6.8 lens too.

mdarnton
11-Feb-2018, 13:40
<obscenities deleted>

I've just added a spreadsheet with the scales and formulas behind them to the list. If you need help finding the list, try the stickies in the lens section.

<obscenities back at you deleted>
Thanks for the assistance.

Moogie
12-Feb-2018, 06:02
Dear forum friends,

Thanks a lot for all your great insights. Now it is obvious that this is a true Goerz and just used the f/stop system different to what is used today.
Still confusing that the two f/stops do not match and that they show different f/stops from different systems.
My one shows 4.6 and then exactly like in the table from the link followed by 6, 12, 24, 48, 92, 192 and 384.
Now to remember the related f/stops which I am used to will take some time but I understand the logic and will save the table on the phone, so I can look it up when needed.

So wonderful from you to help me out. I am very grateful.

Have a nice start in the week, Miguel

Dan Fromm
12-Feb-2018, 06:11
Miguel, if you go to the list and look at the spreadsheet, you'll find the formula. Rearrange it and you'll be able to calculate the f/stops that correspond to the engraved numbers.

Moogie
12-Feb-2018, 06:59
Yes, Thanks a lot Dan. I saved your list already as well :-)