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Schneider Super-Angulon 72mm XL rotating on helicoid mount


rod_sainty2

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<p>My Schneider Super-Angulon 72mm XL lens is mounted on a Schneider helical focus mount and Cambo Wide DS mounting plate, for use on the Cambo Wide DS 4x5 camera. I've just returned from a month-long overseas trip shooting architecture in colour and B&W, which involved frequent changing between the centre filter and red filter. Sometimes, probably due to expansion in the heat, one or other of the filters became stuck and required additional force to remove. Although I attempted to protect the lens from the torque, the lens eventually became loose in the mount. The entire lens is able to be rotated freely within the helical focus mount and the Cambo mount plate. <br>

Back home, a repair technician removed the rear lens group, exposing a blackened brass ring with spanner slots rearward of the diaphragm and shutter. He was surprised to find that tightening the ring did not fix the rotation of the lens, though it did impede it somewhat at first before loosening entirely again as the lens was rotated. He suspects that there is insufficient thread present for the ring to move forwards on to fully clamp the lens, and proposes (if I understood him correctly) to move the shutter assembly forward in order to provide additional thread at the rear. This sounds logical but I'm concerned it may upset the focus adjustment set by Cambo at the factory. <br>

Has anyone experience with this problem and able to offer advice? <br>

Thanks,<br>

Rod</p>

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<p>It sounds like the jam nut was not properly tightened by the technician. The ring has a raised ridge on one side that fits into the hole on the board or the helicoid. Sometimes that ridge is not properly centered in the hole and you think it is tight till it slips off and since it is then loose again does what you are describing.<br>

Or you broke the mount and it needs to be repaired.<br>

Try retightening the jam nut first.</p>

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<p>Thank you, Bob, for your considered response. The feedback from the technician today was that he believes the nut was centered because it was not undone enough to not be centered. He also clarified that he is not proposing to move the shutter forward but, rather, to move the nut back in order to expose more thread. He assured me that the focus will not be disturbed.</p>
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<p>Have your technician dismount the lens from the HFM. On the rear of the shutter there SHOULD be what looks like a very tiny screw, the head of which extends about 1 mm above the rear surface of the shutter. This "screw head" is actually a locator pin, which fits into a corresponding recess in the front face of the HFM... preventing the lens from rotating. Chances are the locating pin is not present. Your tech may have one laying around, or get one from Schneider.<br>

Fear not about disturbing the focus adjustment of the HFM. That adjustment requires loosening three tiny screws in the focus ring.</p>

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  • 2 weeks later...

<p>Paul, you were correct. The technician found that the locating pin was missing. Thank you for your advice.</p>

<p>He didn't have a Schneider pin at hand to replace it, but found a substitute. He had a screw from a Canon lens that had a matching screw thread but a much larger diameter post head. He was able to reduce the diameter of the post head on his lathe. I think that's pretty impressive service in this day and age.</p>

<p>He also commented that it seemed that the original locating pin was never present, as there appeared to be no way it could have escaped from inside the lens. Perhaps the alignment had previously been achieved only by the retaining ring at the rear.</p>

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<p>Hi Dan, hi Bob. I can see how the locating screw might be deemed to be unnecessary by manufacturers if the rear ring is regarded as sufficient, but, unless vibration makes it come out, in what way can it be a nuisance?<br /> <br /> Of course, the problem my technician found is that there is insufficient thread present at the rear to enable the ring to be tightened to stop the rotation. Hence, in this instance, the pin was needed. Can you suggest any alternative?</p>

<p> </p>

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<p>The depth of the threads on a modern shutter and on lens manufactured helicoids is standardized and has been for decades. So the real question is why your shutter has short threads. Or why the retaining ring with your shutter can't properly make use of those threads. Or why your Cambo board is too thick for the standardized thread length.<br>

As the USA Rodenstock distributor since the mid 80s and the Linhof distributor since the 70's we have never came across this problem. And we sell lots of helicoids for view camera lenses.<br>

If it is the board then it is not properly countersunk to the correct depth for proper mounting so this brings up the question if this is the proper board for your camera and lens or is it a board that was just obtained for use with this combination without seeing if a special board was required? If it is not countersunk to the proper depth then doing so could throw off infinity focus unless the countersink is on the back side of the board.</p>

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<p>Rod, if the locating screw is in place and the board on which the shutter is to be mounted doesn't have a notch for the screw, mounting the shutter flush to the board is impossible. This seems obvious but has caught many people. Also, when the screw is used to prevent the shutter from rotating, there's typically just one notch, therefore just one possible orientation for the shutter on the camera. This can be limiting.</p>

<p>Countersinking the back of the board as Bob suggested is one way to make mounting a shutter on a thick, usually wood, board possible. Another way, often used with wooden boards, is to attach a flange to the front of the board and screw the shutter into it. When this is done, the locating screw has to be removed. Think a little and you'll understand why.</p>

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<p>Dan,<br>

He has a Cambo Wide so the only solution is milling the back of the board to the proper depth so the helicod is properly set to infinity. His camera has no bellows so the front flange is not workable and neither is milling the front of the board. It sounds more like he has the wrong board as if the screw was left in and the shutter did not sit flush then he would not have even results across the frame sine the lens is not parallel to the image plane.<br>

Rodenstock does not, and I don't know if Schneider does, put an alignment screw on the rear of their helicoids. So the only way an alignment screw can be in the picture here is mounting the lens to the helicoid and not in mounting the helicoid to the board.<br>

We do have a couple of Linhof Technorama 617 S III lenses in stock which do use Schneider helicoids but since these are new lenses in factory sealed packages I would not open one to check as we can not re-seal the package exactly like the factory can. But someone like Bob Watkins should be able to tell you if you ask as Linhof, Arca, Cambo all use the same helicoids with the Schneider lenses and he does work on all of them.</p>

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