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Thread: Turner-Reich modifications?

  1. #11

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    Re: Turner-Reich modifications?

    Did anyone do the math?
    I get, from the reciprocal of the sum of reciprocals of 19.7 and 25, not 12 but 11", and 12" for 21+28
    Well it's not math but arithmetic, and I'm old , so please verify

  2. #12

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    Re: Turner-Reich modifications?

    Quote Originally Posted by Corran View Post
    I wouldn't expect much from the single elements. I had a 12" TR triple (of the 21/28 type), and both the single elements were pretty bad, even stopped way down.
    Thank you. So those aren't on par with ser.VII Protars.... that makes the TR's of little interest to me, and the only possible alternative is perhaps a Wollensak Ia (bought one also but again haven't got it yet).

    In fact, I was very sceptical about any single elements of any convertibles for years (having tried half-Dagors, Convertible Symmars and Sironars, etc., etc.). But the VII Protar was reported in this forum to be way better so I purchased it, and I really liked it. Wollensak Ia was said to be about as good (except in coverage) - I'll verify that with my own eyes soon.... But I am told different things on the T-R, including that it suffered from a lot of sample-to-sample variations. If it did, I guess my question about the version-to-version difference in just pointless.

    And BTW there also is an older 8/4 Wollensak I (aka Royal Anastigmat) on the 'bay now. Any advice if its singe cells are worth trying?

  3. #13

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    Re: Turner-Reich modifications?

    Quote Originally Posted by EdWorkman View Post
    Did anyone do the math? I get, from the reciprocal of the sum of reciprocals of 19.7 and 25, not 12 but 11", and 12" for 21+28. Well it's not math but arithmetic, and I'm old , so please verify
    That formula is only an approximation. One can get different focal length combinations from the same single cells by changing the distance between those cells. What would the image quality be, is another question....

  4. #14

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    Re: Turner-Reich modifications?

    Answering my own question now....

    I've got several 12" Turner-Reichs of both 'types' at least, the ones with the cells labled 19.7" + 25", and those with 21" + 28" marked cells. The answer is, they all are just identical. The real focal lengths of all the rear cells is 19.7" (circa 500mm), and of the front cells, 25" (635mm). The complete double anastigmats are actually 12". And the 21" and 28" figures are not the real focal lengths but the so called flange focal lengths - i.e. the bellows draw needed to focus the lens at infinity. Listing flange focal lengths in catalogs instead of the 'real' (equivalent) focal lengths was a common practice in the 19th century. Keeping the way outdated 'tradition' well into the mid-20th century looks like a cardsharper's method to boost the marketing....

    But the lenses themselves are quite good, equal to series VII / VIIa Protars in all respects except in coverage which is about 66 for the whole double anastigmats stopped down to f/32. That's just a tiny bit less than the coverage of Wollensak series Ia lenses but far less than the coverage of the original VIIa Protars.

    The unique feature of the Turner-Reichs is their ability to make nice smooth out of focus background already at full aperture; that's true for both the complete double anastigmats and the single cells. (The original VII / VIIa Protars as well as their Wollensak Ia copies need to be stopped down at least about a full stop for their best out of focus background rendition.) That's what the additional lens element does in the T-R cells....

    As for the quality control / centering consistency that's usually said to be questionable, I do not see any problems with any of the 7 cells that I've tested both individually and in different combinations. My tests were not too meticulous but well enough precise to match the actual field usage of the lenses on 8x10". I did my best to buy them as cheap as possible so almost all of the cells have some balsam degradation at the edges. As Turner-Reich cells are not too easy to take out of their brass housings, I am going to heat them up without disassembling first to repair the balsam faults. Then I'd test them again and see if the centering goes wrong after the treatment. If it does, I'll have to dissemble the cells the hard way and recement them properly - and suspect those poorly centered ones that other people talk about from time to time were probably treated in a similar way by some earlier owners and thus went out of alignment well after they left the Gundlach factory....
    Last edited by ridax; 20-Nov-2021 at 05:44. Reason: lens angle of coverage was mistyped (!)

  5. #15

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    Re: Turner-Reich modifications?

    Quote Originally Posted by ridax View Post
    ....there also is an older 8/4 Wollensak I (aka Royal Anastigmat) on the 'bay now. Any advice if its singe cells are worth trying?
    I've got and tested that beast, too. It's single cells are nowhere near the Protar ones and not worth discussing. The complete lens is not bad but also nothing to write home about. Its character reminds me of my G-Claron but the coverage is much less due to the front cell's vignetting (a combination of two rear cells would be similar to the G-Claron in coverage). The series I / Royal Anastigmat is also less sharp then the G-Claron and much lower in contrast as it is not coated. All in all, I've no use for this lens.

  6. #16
    Nodda Duma's Avatar
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    Re: Turner-Reich modifications?

    ridax,

    Ive gotten pretty good at repairing balsam separation in the Turner Reichs, and can confidentially say your first approach wont work. In fact, it will cause the lens to adhere to the barrel as the balsam cement that flowed out to the sides of the lenses when new will melt and reflow, making it more difficult to remove for the separation repair.

    Instead, I would recommend proceeding directly to removing the elements.

    I can also say that if you use the barrel to control centration when you bond the stack back together, then you are recentering as accurately as they did in the factory.
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