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Infinity stop and screw to M adapter.


levegh

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I just put an adapter on to a screwmount 35mm f3.5 Summaron so that I can use it on my M2. It is impossible to move it in or out of the infinity stop because the 'button' will not push down far enough: it is stopped by the adapter. The discrepancy is only about ten thou (sorry, Mr Barnack, 0.25mm) so I can carefully take a Swiss file to it. There is a witness mark on the smaller side of the infinity stop suggesting that, even without the adapter, it was a slight problem. Has anyone encountered this before?

Stuart

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55 minutes ago, levegh said:

I just put an adapter on to a screwmount 35mm f3.5 Summaron so that I can use it on my M2. It is impossible to move it in or out of the infinity stop because the 'button' will not push down far enough: it is stopped by the adapter. The discrepancy is only about ten thou (sorry, Mr Barnack, 0.25mm) so I can carefully take a Swiss file to it. There is a witness mark on the smaller side of the infinity stop suggesting that, even without the adapter, it was a slight problem. Has anyone encountered this before?

Stuart

'Proper' Ltm to M adapters have a cutout so that the infinity lock on such lenses drops into it.  Presumably you have a non Leica or Voigtlander one, both of which work ok but I can't vouch for any of the many cheap ripofs 

Gerry 

 

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Thanks, Romanus, but it is the right adapter. In any case, it is the thickness of the adapter that is stopping the button from moving down further and that thickness is always a nominal 1mm. Another 35mm lens with adapter works perfectly well... it is the wedge shaped part of the infinity stop that it is causing a problem. I will reduce it carefully by 0.18mm which is the amount of the discrepancy, but I am curious to know if others have had a similar problem. My apologies if it is a naive or unnecessary question.

Stuart

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Thanks, but I know exactly how the infinty stop should behave. I apologise for not making myself clear. Forget measurements, if you like: I have just eyeballed the lens and also two 50mm screwmount lenses for comparison. On the two comparison lenses, it is clear that the wedge shaped part of the infinity stop is thinner than the part of the stop beyond which the lens cannot turn. On the Summaron, the two parts are the same thickness. The witness mark which I mentioned appears to have been made while it was on a screwmount camera and the slight wear allows it to operate as it should. I can see perfectly well what I should do to fix the problem, but I was curious to know if anyone else had had encountered it.

Stuart

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It is an odd thing about Leitz' own adapters.  I have 90mm adapters both with and without the cutout.  I have a 135mm adapter, which should be usable as a 35mm adapter on an M2, but it does not have a cutout.

I can see how the Summaron infinity lock might hit the edge of the cutout on the adapters I have.  But don't file the lens; file the adapter.  And the thickness is not "a nominal 1mm"; it must be exactly 1mm.

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Depends what one means by nominal. My measurements of four adapters revealed a variation amounting to a little less than 0.01mm: that does not seem significant. I have not measured a genuine Leitz one. It had already occcurred to me to locally reduce the thickness of the adapter but the question remains... is the discrepancy in the thickness of the wedge shaped part of the infinity stop peculiar to my very limited choice of screwmount lenses available to compare? On a Summar and a Summarit sitting on the desk in front of me, the wedge shaped part has been made thinner than the fixed part. That was done by Leitz. On the Summaron, the 'wedge' had not been thinned. That was also done (or not done) by Leitz. I am just curious.

Stuart

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Stuart,

your Summaron 3.5/3.5 problem made me try to find out what went wrong.

I have no answer if you (as me) use the right Leitz adapter which I use on my Summaron for years without any trouble.

So, just to have a doubt if my Summaron 3.5cm can have the same trouble, the machining of this compact lens is so tight.

Compared to other Leitz lenses that I have, the 3.5/3.5cm lever has a small tilt toward the lens (about 10° not so visible, never saw that till today) and this "tilt" has always been there.

 

Try to unlock halfway, it works on my Summaron 3.5/3.5cm (I think that is the usual way I use to unlock infinity lock).

Edited by a.noctilux
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A specification is the exact design value +/- a manufacturing tolerance.  You see that the specification for the adapter might be 1mm +/- 0.01 mm.  That does not make the 1.0mm a nominal value.  I don't know what the design tolerance actually is.

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I had a similar problem recently putting an early pin-push Elmar on an M4P.

Solved it by turning the lens away from the infinity position before screwing it into the adaptor so that the infinity catch was clear of the adaptor when screwing it on, then put the lens back to infinity where it lined up with the cutout in the adaptor instead of jamming on the non-cutout part of the adaptor..

just checked again, the problem I had was with an 11 o’clock Elmar which jammed against the adaptor because it was still not in the cutout area of the adaptor when screwed in.

so you need an adaptor that has a cutout where the infinity catch rests at the infinity position. Turn the focussing away from infinity while screwing the lens and adaptor together. I have a mixture of adaptors and I had not noticed until now that even two otherwise identical Leitz 90mm ones are different, one has a cutout and the other doesn’t. You can always make your own cutout in the right place if your adaptor does not have one.

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Edited by Pyrogallol
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Just tried another adaptor which is almost all cutout, it goes with my 21mm f4 Super Angulon, even that does not have the cutout in the 11 o’clock Elmar position.

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a.noctilux, I now have slight tilt when the infinity lock is in operation. I am slightly surprised. Presumably there is a little tolerance which allows the tilt.

zeitz, I apologise for imprecise use of language. I have no idea what the original specification was. 1mm plus or minus tolerance of whatever it is, presumably. As a non-engineer, I used 'nominal' to mean the stated value, but of course it could just as easily have been 0.999mm or 1.001mm.

Pyrogallol, I tried that and it sort of worked, but a few strokes with a very very fine file has solved the problem. To those who regard even the underneath of the infinity stop as sacrosanct, I humbly apologise.

Stuart

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21 minutes ago, levegh said:

a.noctilux, I now have slight tilt when the infinity lock is in operation. I am slightly surprised. Presumably there is a little tolerance which allows the tilt.

zeitz, I apologise for imprecise use of language. I have no idea what the original specification was. 1mm plus or minus tolerance of whatever it is, presumably. As a non-engineer, I used 'nominal' to mean the stated value, but of course it could just as easily have been 0.999mm or 1.001mm.

Pyrogallol, I tried that and it sort of worked, but a few strokes with a very very fine file has solved the problem. To those who regard even the underneath of the infinity stop as sacrosanct, I humbly apologise.

Stuart

Just look at those as tool, then every tool must be adapted before adopting it to make the job required.

...

 

Thanks

you confirm that those circa 10° tilt is normal on Summaron 3.5/3.5cm.

Edited by a.noctilux
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"Your comment appears to indicate that you are not using a genuine Leica adapter, or am I missing the point? "

Matlock, I am not sure what point you are making. When it is pressed, the bottom of the button release for the infinity stop touches the adapter. The adapter is within one percent of the correct thickness of 1mm. (1mm is my assumption: it is not likely to be wrong, surely. What would be the point of Leitz specifying a tiny difference from a round figure?) The wedge shaped entry into the stop is deeper than on my other lenses. The resulting space between the 'wedge' and the adapter is very slightly too small to allow the 'button' to pass through. With the exception of the adapter, all parts are Leitz and the adapter is the correct thickness. In what way would the correct Leitz adapter help?

In fact, I have now fixed the problem. The focus moves to infinity with a slight but satisfying click.

Stuart

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2 hours ago, Pyrogallol said:

Just tried another adaptor which is almost all cutout, it goes with my 21mm f4 Super Angulon, even that does not have the cutout in the 11 o’clock Elmar position.

How do you get that adapter off the camera body?  The prongs on the rear cap would be of no help!

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