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Thread: Iron ring on brass lens - possible to get off?

  1. #31
    Between here and there
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    Re: Iron ring on brass lens - possible to get off?

    I have to have a look more closely tomorrow at the lens. I am thinking I need to get the front cell out and the rear cell (already taken out before), and then see what I'll find out from the inside.

    I'll see what I can find out about the solder. Since the iron ring is straight cut and the aperture ring itself is bevelled, there is a bit of space, where the solder might have run down. But in that case I am not sure the aperture would even move (solder seeping down in the crack) - which it does.

    I can supply a few more close-ups if someone feels like it.

    The lens is labelled "Rapid Weitwinkel Aplanat F12 Serie III No. 3" with a serial number 55212. It was advertised as an Emil Busch, but I have no idea how the seller came to that conclusion. In this particular case, there is very little evidence of the lens being anything even remotely valuable.

    I have not much in the way of advanced tools, so I am just going to go easy on this one. Or just bury in the woods and make a treasure map.
    "Be still and allow the mud to settle."

  2. #32
    Gary Beasley's Avatar
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    Re: Iron ring on brass lens - possible to get off?

    I would take a screwdriver in put in the gap between the iron and knurled ring and twist gently. If it moves swap to the other side and do the same, back and forth till it comes loose. As soon as theres room enough put a cushion, maybe a popsicle stick on the brass side to limit the scratches.

  3. #33

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    Re: Iron ring on brass lens - possible to get off?

    Which runs a extremely high risk of denting, deforming or damaging the parts involved. Twist of a screwdriver blade will impose several hundred to thousands of pounds of force on to a small area easily causing damage.

    Think in dimensions of 0.001" and metal being more like rubber that might not bounce back once bent.

    Not a good idea.


    Bernice


    Quote Originally Posted by Gary Beasley View Post
    I would take a screwdriver in put in the gap between the iron and knurled ring and twist gently. If it moves swap to the other side and do the same, back and forth till it comes loose. As soon as theres room enough put a cushion, maybe a popsicle stick on the brass side to limit the scratches.

  4. #34

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    Re: Iron ring on brass lens - possible to get off?

    I have obtained lenses and other items that were stripped from scientific or industrial units, that have been modified (better or worse) for their application... I have gotten used to strange stuff on them that does not affect my application, and even sometimes can help to allow a new upgrade...

    Don't obsess over it... ;-)

    Steve K

  5. #35

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    Re: Iron ring on brass lens - possible to get off?

    Is the “solder” possibly just remnants of whatever was on the outside rather than holding the ferrous ring in place? Doesn’t seem to be the best way to affix the ring, plus appears to be a good space between the iron ring and the knurled ring. Why isn’t there more material on the brass?

    Looking at the front of the lens, there seems to be a significant space between inner iron and outer brass, at least from then angle we are shown. Is the space the same all around? Is the iron round or oval? Or slightly so?

  6. #36

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    Re: Iron ring on brass lens - possible to get off?

    A final input - Simplistically a ferrous [we do not know if it is iron or steel] ‘ring’ has been placed over an external ‘tube’ of the lens. The ‘fitting’ of the ferrous ring to the lens tube is either a sliding fit or a loose fit. A press fit would involve temperature variations and other complications.

    The ‘ring’ is butted against the ‘tube’. The worse-case method of attachment would be a solder washer, paste or other material placed between the butted surfaces. The better-case method would be a bead of solder/other material around the periphery of the joint line between the two objects.

    The amount of smear/splatter on the outside of the ‘ring’ implies a lack of expertise by the applicant.

    It is not known if the axis of rotation of the ‘ring’ is coincident or parallel or skewed to that of the ‘tube’. The actuality infers the use or not of a three or four jawed chuck on a lathe.

    Given the ‘better-case’ method of attachment and the implied competence of the application, it may be possible to ‘scratch away’ the bead to enable the two elements to be split.

    Have fun

    Regards

    Tony

  7. #37
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    Re: Iron ring on brass lens - possible to get off?

    So, I am happy to report that the lens actually is a Rodenstock, as I suspected.

    I took a scalpel, running it around it the inner perimeter, as an attempt to loosen any solder that might have gotten in between the aperture ring and the iron. With a highly advanced tool (read: kitchen knife) I very gently twisted. Then I applied some oil. With the gap widening, I got enough leeway to pull the ring off slowly. The iron ring had rusted, and there was no solder on the inside of the ring, only a bit on the back. The ring was press fit, and the solder was only used to attach the hood contraption.

    Given the rust, there is a large amount of scratches on the brass. It is never going to be a show piece, and the verdict is still out on the pictorial qualities of the lens (probably nothing to write home about), but hey, it was a bit of an adventure (to me at least).

    Thanks everyone of you, heaping advice and jokes along the way.
    "Be still and allow the mud to settle."

  8. #38
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    Re: Iron ring on brass lens - possible to get off?

    I dug through the archives trying to figure out more about my lens, and came across this:

    „I do have a very nice Rodenstock catalog from 1914 (in German), and while it doesn't specifically mention the Perigon, it does include an f12 Serie III Weitwinkel-Aplanat that was available in four focal lengths (9cm, 12cm, 16cm and 22cm). Stated coverage is 100 degrees. I assume this coverage is wide open, as the spec table lists even greater coverage (~106 - 108 degrees) at smaller stops (Kleiner Blende). This equates to an image circle of 32cm for the 12cm focal length and 44cm for the 16cm lens.“

    (from the below link, first post by Kerry Thalmann):

    https://www.largeformatphotography.i...l=1#post151182

    Putting my lens on the camera, I get about 16 cm at infinity, so from this, I can assume mine is the 16 cm version, since the serial number puts it at early 1910’s. And given the above coverage at small stops, at 44 cm, I guess the lens will be a bit of a waste on 5x7“ – need to go bigger …

    It has an f/stop sequence of 12 18 25 36 50, so I guess the f/12 is about f/11-ish and from there on onwards.
    "Be still and allow the mud to settle."

  9. #39
    Ron (Netherlands)'s Avatar
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    Re: Iron ring on brass lens - possible to get off?

    Quote Originally Posted by Jimi View Post
    It has an f/stop sequence of 12 18 25 36 50, so I guess the f/12 is about f/11-ish and from there on onwards.
    It seems your lens has a mix of the old German f-value system and the old Stolze/Goerz system:
    f4.5 6.3 9 12.5 18 25 36 50 71 100

    here some tables relating older and more modern f-stop systems:

    https://camerosity.files.wordpress.c...07/sp08_a1.gif

    http://randcollins.files.wordpress.c...agmnumbers.gif
    Last edited by Ron (Netherlands); 12-May-2020 at 11:02.
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