How to enhance lens focusing smoothness? (summicron)

amoz

amoz

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Hi all,

I have recently purchased a second-hand summicron 35 asph and while it is in very good condition, I have my doubts about the smoothness of the focusing tab.

When traveling over larger distances, say changing focus from 0.7 to 5 m at once, it feels very smooth. When small adjustments have to be made, however, it is somewhat ridgid and one has to put a little extra pull/push force onto it. This really makes it hard to detail-focus.

By the way, my tiny little Voigtlander 35/2.5 pancake is smooth all the way, also when traveling just a little bit, so I figure this should also be the case for the 'cron.

My question is: where should I smear the vaseline? :rolleyes: Seriously though, is this something you recognise and can it easily be "fixed"?

Thanks!
 
amoz, to do it well you need to disassemble the lens (which requires the correct tools). Also, you need the correct greases (right visosity, little vapours, ...).

If you have no experience with this I recommend getting it CLAd by somebody with more experience.
 
Try cleaning the "lens barrel threads" (don't know the right term) from the rear of the lens with cloth or something. You know, when you move the focusing you can see those threads from the rear...they might be dirty. I had a very stiff 50mm summicron once and I just rubbed those threads many times and it helped a lot. And after that I did put one very small drop of liquidy lubricating stuff to those threads and with these actions I didn't have to cla the lens. I am not recommending that lubing with your lens...but it did not hurt mine.
 
amoz said:
When traveling over larger distances, say changing focus from 0.7 to 5 m at once, it feels very smooth. When small adjustments have to be made, however, it is somewhat ridgid and one has to put a little extra pull/push force onto it. This really makes it hard to detail-focus.
Click to expand...
You're experiencing a difference between static and dynamic friction. It will always be there to some extent.

Of course, there can be reasons that it's worse than should be, and if so, take Magus's advice. But you may notice that the dynamic behaviour also becomes smoother..
 
I have noticed this with several more recent Leica lenses. One, a 90mm Summicron AA, was so bad it had to go back for service - it was unusable.
 
Get a professional CLA done by someone like DAG. These modern ASPH lenses have terrific optics but in my experience the build quality is crap. I've had two 24/2.8 lenses and two 75/2. Both the replacements are not really right either - the first one in each case was seriously wrong. I have a 90 AA that went back to Popflash after the "exercise the lens" lark didn't work. The only one that's perfect is a used 35 Summilux ASPH that was 3 years old when I bought it. If a lens costs in excess of $2K or $3K I think you have a right to expect that it's OK. These modern lenses are just not worth the aggravation - no more for me! :(
 
I also have a 90 AA that had to go in for the same problem. I bought it 2nd hand and sent it to DAG for relube with a hevier lube. Now it's fine but the lube is much hevier. My 50 tabed summicron developed wear in the helix due to upward pressure during focusing with the tab. At 3ft there was a stick spot which just happened to be at the point where the strongest upward pressure was on the focusing tab. I wound up selling it. MY 35 summicron v4 developed a wobble due to the same upward pressure during focusing. I also sold that lens. My 50 asph summilux 50 is developing sticky spots also. I must say that I'm not impressed with the construction of leica lenses since the mid 70's. It's very disappointing for lenses of this cost.
 
I dropped a 50mm summi and bent the helical focusing gear. A "repairman" worked on it and advised me to rack the focus back and forth while I was watching t.v. to loosen the focusing. I did this for about two weeks and it certainly did help the stiffness. It never got close to the silky smooth focus I loved with this lens. I finally sent the lens to Sherry Krauter and she replaced the gear and worked some magic to bring the lens back to the buttery smooth focus.

While it took some time to coax the parts from Mother Leica it was worth the wait.

Bob
 
I also bought my 35 summicron ASPH in near-new condition and have the same issue. I sent it to Sherry Krauter along with my camera for her to look at. Her opinion was that it was not worth working on, and that it probably wouldn't get much better if she did. I will be trying Magus' method.
 
Thanks for all the replies! I'm glad I am not the only one with this issue. As Jake suggested, I will start of with the least scary approach :)...

I'll let you know how things work out.
 
I really think these lenses need to "bed-in", I think Magus has hit the nail on the head. A former colleague had the same problem, and "working" the lens got it nice and smoooooth :)
 
where did i read that leica has a special setup that exercises the focusing ring at the factory before shipping out, so it's already perfectly smooth when you get it?
 
I will add my voice to the chorus. My little chrome 50 Elmar has the same problem: smooth on long and fast focus excursions, slightly sticky (and slightly frustrating) with fine focusing. I've been trying the "Magus' method" (that does have a certain ring, doesn't it?) off and on for a couple of days. I'll also post with my results.

It is interesting though, how my new-ish Zeiss 35 Biogon has perfectly smooth focusing no matter the situation.
 
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Lapping-in (Magus' magical method) is a standard procedure (and probably the best) to smooth out the action of two metal surfaces which rub against one another. Musical instruments, such as trumpets and French horns, have piston or rotary valves which have very close tolerances and often are 'sticky' when new. The best way to free them up is to work the valves until the tolerances are correct. This may have to be done with instruments costing as much as $5000 or $6000.

Of course, if an older lens has this difficulty, it may be that the helical lubricant has dried out, and working the focus may not help much. More radical measures will work, but I'm not going to suggest what to do, for fear of being blamed if things 'gang agley.'

Richard
 
I got great results using Ti-Prep Anti-Seize Lubricant on the focusing threads of my 1949 Elmar. First clean off the old threads with common oil, to disolve any old crud. I got a tube from a bike shop.
 
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