Losing the 'rangefinder coupling'

[reddot925]

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Could somebody please be so kind to explain the below case when using non Leica lens on the M9/M10 to me please, and how do you fix it, do we remove the lens and mount it back again or something else?   Thank you!

 

 

"In practice, the rangefinder coupling disengages below 0.9 meters on my sample. According to members of the RFF forum, it is caused by a shorter focus lever than the one built in Leica lenses. Some users did succeed to fix the issue but I have not attempted it since I seldom need to go below 0.9 meters in street photography. This being said, it means that one will have to always remember as he converges towards the minimum focus limit, that he risks to lose the rangefinder coupling."

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[Frase]

Could somebody please be so kind to explain the below case when using non Leica lens on the M9/M10 to me please, and how do you fix it, do we remove the lens and mount it back again or something else?   Thank you!

 

 

"In practice, the rangefinder coupling disengages below 0.9 meters on my sample. According to members of the RFF forum, it is caused by a shorter focus lever than the one built in Leica lenses. Some users did succeed to fix the issue but I have not attempted it since I seldom need to go below 0.9 meters in street photography. This being said, it means that one will have to always remember as he converges towards the minimum focus limit, that he risks to lose the rangefinder coupling."

It only really matters on older film bodies, when I use my 50mm summicron on my button rewind M2 the lens can focus closer than than the body. The rangefinder stops moving at .75m while the lens can actually focus down to .65m.

[reddot925]

Thank you , does that mean this will not affect digital bodies ?

[Frase]

Thank you , does that mean this will not affect digital bodies ?

Yes all leica lenses will focus to the same distance as all current Leica bodies

[reddot925]

Sorry this question is for non leica lens, but with Leica digital bodies.

 

I'm considering this lens and was hoping you said losing rangefinder coupling does not happen on digital bodies.

Edited May 25, 2017 by reddot925

[Frase]

I would think that the minimum focus distance on current M bodies is about .65m after that unless you are using live view you will have parallax problems.

[michaelwj]

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When you take the lens off you see the roller can in the top of the lens mount just inside the body. With no lens it is as far out as it goes. This corresponds to the minimum focus distance that the rangefinder will measure (0.7m typically). All the way in corresponds to infinity focus. There is a corresponding part on the lens that moves in to the camera body as you focus to infinity and away from it as you focus closer. Some lenses, especially ZM and CV lenses have the ability to focus closer than the RF cam will move; i.e. The lens moves further away from the body, and the roller cam is in the position it is in when no lens is attached. This is losing rangefinder coupling - the lens is no longer coupled to the RF mechanism in the body. Some lenses not wholly compatible with the Leica M mount will lose coupling before 0.7m.

[reddot925]

Thank you @michaelwj , and once you lose the coupling what do you need to do?

[michaelwj]

Thank you @michaelwj , and once you lose the coupling what do you need to do?

Then you're scale focusing. So you measure with a ruler or tape measure or you guess. Or use live view.

Edited May 26, 2017 by michaelwj

[reddot925]

Sorry I mean how do you gain the coupling back ? Unmount and remount the lens or simply focus longer and it will couple back?

[spydrxx]

The easiest way is to run the focus of the lens back to infinity to assure full coupling.

[reddot925]

Thanks @spydrxx good to know there's no need to unmount the lens.

[lct]

Sorry I mean how do you gain the coupling back ? Unmount and remount the lens or simply focus longer and it will couple back?

 

It will couple back automatically when focusing at 0.7m and above. There is no need to unmount the lens nor to focus at infinity at all.

[reddot925]

That's great to hear!  Thanks.

[Exodies]

Perhaps the word "uncoupled" made you think of railway carriages. It's not like that.

[earleygallery]

That's great to hear!  Thanks.

 

Look inside the lens mount, at the top. That's the rangefinder cam you can see - touch it gently and it moves inwards, let go and it springs back out.

 

Look at the back of your lens (unmounted). Turn the focus ring and you'll notice how the rear most ridge moves in and out?

 

When the lens is on the camera, as you focus, that ring moves the rangefinder cam and that's how the focus mechanism works.

[lct]

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Simply register for free here – We are always happy to welcome new members!

[helged]

I just got my hand on an M8, seeing little use in recent years, I assume. The sensor looks very clean, so that's good news. However, the roller has a tendency to get stuck at the inner position. I guess there is a need for lubrication and/or a new spring or something. Any suggestions what I can do without sending the body away for a CLA? On another forum, I see that it is suggested to put the body in the sun for some time, to warm the lubrication. I assume this is not the recommended way to solve the problem (something I have not tried, yet...).

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Hallo,

Look here: Leica M

[jaapv]

You can work it  back and forth a bit to see whether you can get it to move freely again. Heating seems to me not to be an optimal solution: the first day of winter will get it stuck again. It should not be too expensive to have it seen to by a third party repairer.