Summicron 75 jerky focussing at low temperatures?

[Christoph13]

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Hello

I am exploring the long end of the Leica M lens spectrum, the APO Summicron 75 to be exact. I really love what I have seen so far in terms of images this little gem is able to produce.

I am less thrilled about the focussing action and I found a couple of threads relating similar experience. The symptom is this: When focussed in the close range, it is next to impossible to focus the lens in one smooth movement to infinity. The friction increases and gets stuck approximately half way through, sometimes very firmly so. The first time I experienced this, I was sure I had focused to infinity because it felt like the focusing ring hitting the firm stop at the end of the movement range. This is very reproducible, the cure is simple enough, one has to let go (i.e. remove what little force may be left on the focusing ring) and then the focusing movement can be completed as normal.

Now, I understand that the addition of a second, independently moving lens group makes the focusing more complex, so what I am experiencing may be the point where the floating element kicks in (or out). However, in the short time I habve been able to use this lens I noticed that this behaviour is strongly temperature related. At room temperature the focusing action is acceptable, one feels that something is going on under the surface but going through the entire range in one go is no problem at all. Outside, at temperatures around 3°C the transition is much less smooth and downright annoying.

Is this specific to the particular lens I am trying out here or do others have similar experiences?

 

Thanks

Chris

 

PS: I find the camera-centric division of this forum strange. There are specific forums for certain camera models, but lens-specific issues (which could be used on different camera models, film, digital, whatever) are all over the place. My take is that lenses are the main concern and I'll be happy to use whatever camera accepts them.

[elgenper]

Must be your copy. I use mine extensively here in Sweden, in temperatures well below 0 deg C; sometimes below -20 deg C. Butter smooth focussing all the time, all the way.

[cbretteville]

The 75/2 and my 50/1.4ASPH shares a lot of dna. I can feel the floating element being engaged when focusing from longer to shorter distances, but can't say I have ever noticed anything when focusing from close to distant objects. "Half way through" also sounds like the helical should be beyond where the floating element is engaged.

 

I'd say your lens needs a trip to Solms. I have an Elmarit-M 90 that exhibited similar symptoms (no floating element). A trip to CS in Solms fixed it, for a fee.

 

Carl

[Christoph13]

Thank you, gentlemen, that's what I had hoped to hear. Although my wishful thinking made me read "fixed it for free"

 

 

It turns out that the stickiness is at least in part caused by the lens sitting around unused for quite a while. Is it possible that the grease gets sticky to the point of causing the lack of smoothness in the focussing action that I observed? And perhaps more importantly, can it be cured by simply using, i.e. moving the focusing ring, or does the grease deteriorate permanently?

I am asking because in general I really like the lens but admit to getting nervous about this particular example.

 

Lots of questions, I know

 

Christoph

[01af]

Is it possible that the grease gets sticky to the point of causing the lack of smoothness in the focussing action that I observed? And perhaps more importantly, can it be cured by simply using, i. e. moving the focusing ring, or does the grease deteriorate permanently?

Well ... mine was a bit jerky when I got it (previous owner said he had hardly used it), and it got significantly smoother—just fine, actually—after turning the focussing ring a few dozen times from infinity to 0.7 m and back. However in the beginning it wasn't anywhere close to being as bad as you described it.

[pico]

A newer lens (say, one less than 7 years old) should not have that problem. Exercise it and if the problem does not completely go away, a CLA is mandatory.

 

I've been using my old Summilux 35mm this Winter and it has begun to show similar symptoms at < 0c (32 F). A CLA is in order. OTOH, the 75mm Summilux is perfectly smooth.

[ho_co]

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Christoph, when I worked for Leitz and the repair department received a lens whose focusing was "sticky," they simply put the lens on a jig which focused the lens repeatedly back and forth over the entire focus range. That was the time of the large helicoids of the 90/2 and 135/2.8 with separable heads, and the idea was simply to wear in the grease.

 

I don't know if that's still done with lenses with floating elements.

 

If the focusing isn't smooth, I would definitely send it to Leica for assessment.