RÜO Dopp-Anastigmat Iricentor

JPD · Mar 27, 2009

I got this lens today, marked: RUO DOPP-ANASTIGMAT IRICENTOR 1:6,8 F=18cm OPT-WERKE RUDERSDORF-BERLIN No 2139 in an early working Compur.

The "Vade Mecum" says it's a Dagor type, and "a really good design" according to W. Frerk.

Most of the RÜO lenses I find on the internet have low serial numbers. I wonder how long Optische Werke Rüdersdorf were in business?

The lens is very clean and scratch free, but has a light yellow tinge. Not much, only as an old UV-filter. What could that be? Yellowing balsam? The glass?

Ole · Mar 27, 2009

There isn't much I can find out about Rüo-Optik, but there are a few leads:

The first patent I can find under the name Rüo-Optik is dated 9/11 1920, for a projection lens. yet the same constructor (Hahn) patented the Rüo-Tele-Anastigmat 25/2 1919 under his own name. So the company seems to have been set up between those dates - other wise why would he include the "Rüo-" in the name of the earliest lens and not the later? I would guess that the company was in planning but not yet registered in February 1919.

Hahn seems to have specialised in fast lenses. Among the Rüo products are the Calinar f:2-2.5, later f:1.5-1.8, and the Paritar f:1 (1) from 1933. I wonder what the T-stop was on a 5-element 5-cell uncoated f:1 lens?

And yes, a light yellow tinge in a lens of that age is very likely to be yellowing of the balsam.

JPD · Mar 27, 2009

Thanks for the information, Ole. I see that the municipality of Rüdersdorf has a web page. Maybe they can give some information about when this firm was active. Worth a try.

I wonder if UV-light could bleach the yellowed balsam?

I wonder what the T-stop was on a 5-element 5-cell uncoated f:1 lens?

Interesting question. Hm, internal reflections... Some reaches the film... Could it be more than 1 stop?

Ole · Mar 28, 2009

No, UV light is not likely to bleach yellowed balsam - it's more likely to make it even yellower.

If each surface reflects 5% of the light, the transmission will be 0.95^10, or about 60%. 5% is pretty optimistic, so I would guess that it loses more than a full stop.

JPD · Mar 28, 2009

But... yellowed balsam in lenses with radioactive elements is bleached with UV light? Worth a try, since I'm only shooting b/w anyway.

Ole · Mar 28, 2009

No, in lenses with radioactive elements it's the glass itself which turns yellow. The radioactivity creates F-centers in the glass structure, which can be removed by application of high-energy light - i.e. UV light.

Balsam yellowing is a result of oxidation and recrystallisation of the balsam, which is a very different process.

JPD · Mar 28, 2009

Ah, thanks for clearing that up! The tinge is very faint, so it's probably best to leave it as it is. I will try the lens this spring.

IRICENTOR · Jun 7, 2009

Hello Ole, I found your words abaut RÜO by searching for information about this company.
Rüdersdorfer Optische Werke is known in Rüdersdorf by only a handful of people. I can find two patents of lenses on the DPMA´s page - Deutsches Patent und Markenamt ( www.dpma.de  you can change the page´s language ) -. One from the 29.09.1923 and one from the 14.06.1928. Both patents are submitted by - Opt.Werke Rüdersdorf G.m.b.H. und Hugo Hahn in Rüdersdorf i. Mark
But I´m not able to find the patents you mentioned. It would be great if you could tell me about your source. Thanks a lot for that!

Ole · Jun 7, 2009

I believe I found most of the information in Hartmut Thiele's "Deutsche Photooptik von A-Z", probably also something in David's "Photographisches Praktikum".

JPD · Jun 7, 2009

IRICENTOR, another Iricentor owner?

IRICENTOR · Jun 9, 2009

Thank You very much for this informations
And - No I m the owner of a single RÜO - Anastigmat TELE and a Tular in a no name plate camer 9 x 12
I m locking for a IRICENTOR

IRICENTOR · Jun 9, 2009

Thank You very much for this informations
And - No I m the owner of a single RÜO - Anastigmat TELE and a Tular in a no name plate camer 9 x 12
I m locking for a IRICENTOR

JPD · Jun 9, 2009

I tried my 18cm Iricentor last week, and it compared very well to my Steinheil Orthostigmat 13,5cm. Both of "reversed Dagor design". Sharp and good contrast.

JPD · Aug 25, 2018

I bought a Voigtländer Avus 9x12 that had bad lightseals and a non-working Compur, replaced the lightseals with velvet ribbon and cut washers from a DVD case so I could mount the Iricentor. The yellowed balsam is even, so it should work as a very light yellow filter. I was wrong in the above post. The Iricentor is a true Dagor design. The gentleman who owns the oldlens.com site sent me the RÜO Optik catalog page for the Iricentor.

The outer diameter of the lens is 32,3 mm. The Voigtländer lens hood fits, but not the B+W push-on filters.

lobitar · Aug 25, 2018

According to Hartmut Thiele - '150 Jahre Photooptik in Deutschland 1849-1999' - the Rüo-Optik GmbH, was founded in 1919 as Optische Werke Rüdersdorf GmbH. Hugo Hahn was formerly designer at Goerz. 1934 bankrupted and designs acquired by Askania-Werke, Berlin.

JPD · Aug 25, 2018

lobitar said:
According to Hartmut Thiele - '150 Jahre Photooptik in Deutschland 1849-1999' - the Rüo-Optik GmbH, was founded in 1919 as Optische Werke Rüdersdorf GmbH. Hugo Hahn was formerly designer at Goerz. 1934 bankrupted and designs acquired by Askania-Werke, Berlin.

Interesting. I wonder if they still made camera lenses in the early 30's. I have never seen a RÜO lens in a rim-set Compur.

lobitar · Aug 25, 2018

In more than 40 years with plate cameras I don't think I ever had a Rüo lens, but same author lists a Caleinar f.1,5-1,8 for 1930 and a real fast Paritar f.1 (!) for 1933. All i can tell.

JPD · Aug 26, 2018

lobitar said:
In more than 40 years with plate cameras I don't think I ever had a Rüo lens, but same author lists a Caleinar f.1,5-1,8 for 1930 and a real fast Paritar f.1 (!) for 1933. All i can tell.

I can find a little about the Caleinar and it's a cine lens but also a small format camera lens. The Paritar may be a cine lens. There is a 10x15 camera on an auction site with a high Buy it now price, that has a 3,5/18cm Hekistar. It's rare, but still "only a triplet".

The 18cm Iricentor is a keeper, a nice little longer lens for 9x12 and I think I'll take it with me on a day trip to the mountains later. I should find fitting filters first.

lobitar · Aug 27, 2018

Yes, the Iricentor is no doubt another nice find (ref. the Linear). If I wanted more lenses (which I really don't as it would just hamper my photography) I might be tempted to look at Sweden again, as I seem to remember having seen some nice specimens over there (I stopped looking when the swedish eBay wouldn't accept my eBay log-in any longer). By the way I bought my first real usable plate camera in Helsingborg abt.1970. It only had a plain Aplanat - which however gave very nice - in fact chockingingly nice - 9x12 Ektachromes. But congratulations with your iricentor and happy shooting!
Forgot to ask: Has the Iricentor focus-shift like most Dagors?

JPD · Aug 27, 2018

lobitar said:
Forgot to ask: Has the Iricentor focus-shift like most Dagors?

I have only taken one test shot so far with the Iricentor, focused at infinity fully open and then stopped down to 12,5. The focus was still spot on. And I didn't notice any focus shift when I tried the 130mm Goerz Berlin Dagor either, and that one was focused at about 3 meters. And I see no visible focus shift on the groundglass when stopping down. If it's there then it's very small.

I'm curious to see how the Iricentor performs at 6,8 and 8, if it has the "Dagor glow". The Steinheil Orthostigmat certainly has the glow, and traces of it even at 12,5, and it's a "reverse Dagor" in design. I'm waiting on another 9x12 Avus to mount the Linear on. I have plenty of Voigtländer plate holders with sheet film adapters, and I don't want to bother with a new camera system and lens boards.

lobitar · Aug 28, 2018

One of the very few lenses I've found this year is a 130 mm Dagor, also without a trace of focus shift. But one has to be a bit lucky, it's not a given. I agree the Avus is very nice as a basic camera on account of general quality and especially the standard 'Normalfalz'-type of cassettes.

RÜO Dopp-Anastigmat Iricentor

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