DR Summicron keeps going off calibration

[pklein]

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I have a DR Summicron that keeps going out of adjustment. It's "gelded," meaning that years ago, DAG ground down the close-focus cam so it wouldn't hit the innards of digital Leicas when mounted. That way, I could use it with the RF in the normal range, and it still would work with Live View in the close range.

When I first got it back from DAG years ago (during the M8 era), it was front-focusing badly with the RF. I sent it back to DAG, who recalibrated it. He said that it was focusing properly when he first sent it back to me, so something must have happened during shipment. Once I got it back the second time, it worked fine. But now, it is front-focusing again. The RF setting is only within the DOF at f/11 and f/16. I only used the lens occasionally, and never dropped it or subjected it to any major shocks. So I don't understand what is happening. But since it has gotten out of adjustment twice, I'm wondering if there is something wrong with the mechanism that causes it to keep going wrong.

Is it worth pursuing this any further? I love the lens. It combines good sharpness with a tendency for highlights to bleed slightly into adjacent areas in an attractive manner. The latter is my definition of "Leica glow." Then again, if it's going to keep doing going out of adjustment, I don't want to waste any more money on it. 

Do any of you have any idea what might be happening? What might be wrong with the mechanism? And who might be the best repair person to troubleshoot this? I know they are all very busy. I don't want someone to make a routine adjustment, only to have it happen again. I suppose, worst case, I could just use it as a Live View only lens. Or try to find a matching "Rigid Summicron" mount for the optical cell's actual focal length.

Any thoughts? 

 

Edited 13 hours ago by pklein

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[TomB_tx]

Are other lenses on the same camera focusing correctly? I once had a dual-range knock a camera RF off when mounting it.

Looking at the lens construction I don't see what could go out - seems very solid. I do hear of the close-focus goggles getting out of alignment.

[lct]

My favorite 50/2. Just to understand, does it front focus in LV mode?

[pklein]

1 hour ago, lct said:

My favorite 50/2. Just to understand, does it front focus in LV mode?

No. I can focus in LV and resulting pictures are in focus. But then the RF is way off.  All my other lenses focus properly, considering their focus shift. And TomB_tx, I don't use the goggles. I can use the close focus range in Live View if I push down on the little "ball bearing" that the goggles would push down on when moving the focus ring between the two ranges.

See the 50% crops below. These were focused with the RF and not moved when changing stops.  Left is closer to the camera and right is farther away. RF focus is on the 20" mark. F/5.6 is barely OK, the true focus point is just outside the DOF. Only at f/11 does the is the 20" mark move inside the zone of critical focus, viewed at 100%.

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Edited 10 hours ago by pklein

[lct]

Looks like an RF issue but it is a special lens that has been modded by DAG so i would ask the latter if i were in your shoes.

[Vanillasludge]

Does the lens focus at infinity in live view?  Can the rangefinder coincide at infinity?