Leica LTM Summar lens polishing?

Leica M39 screw mount bodies/lenses
Bill,

I have had coated lenses polished & recoated - Arax are very good and it costs around $50 depending on the lens.

However, I have heard that polishing a non-coated lens will change its characteristics. If you think about it, you will have to remove some of the surface, so you now have less glass than before (in the coated lens, it's normally just the coating that gets polished off).
 
"However, I have heard that polishing a non-coated lens will change its characteristics. If you think about it, you will have to remove some of the surface, so you now have less glass than before (in the coated lens, it's normally just the coating that gets polished off)."

--Absolutely true. Changing the thickness of the lens changes its formula.
 
Actually, my experience with John Van Stelton was that polishing and recoating does not change the fundamental geometry of the lens. John polished the taking lens of a Rolleiflex 2.8E for me that had some pretty horrendous marks in the coating right in the center of the lens. He told me that if you can feel the scratch with a fingernail, that it is probably not worth polishing as it _would_ change the lens's geometry. But the service he provides does not remove enough material from the lens to make a practical difference. FWIW, he did a great job and resurrected a camera that I thought was going to go for parts. I see that you are asking about an uncoated lens. It might be worth asking the pros to see what their response would be. John is honorable and a great craftsman -- he'll give you the straight dope.

Ben Marks
 
OK guys, I don't know for sure about uncoated lenses - it could be that a very light polish and coat will work. I would just be worried that the optical formulation had changed - even if ever so slightly.
 
My question is if you polish and re-coat, can the lens be shimmed to focus correctly with the changed optical formula? (My Summar could use some help, too.)

With my limited and non-mathematical understanding of optics I'm guessing the answer is no - changing the geometry of the front element should just change how the light is collected, probably increasing spherical and chromatic aberration. If enough glass is removed the cure could be worse than the disease. Experts weigh in please!

- John
 
last week i opened a similar thread, see here:

http://www.rangefinderforum.com/forums/showthread.php?t=45775

i figured out to leave my summar as it is, use it for vintage portraiture and use a shade... the suggestions were mainly that a.) it is extremely difficult to extract the front element from its shim, and b.) it is likely more the haze inside the lens that causes extreme flare (like in my lens). very good coments in this thread!

i am still looking for a way to get deeper inside the lens to clean the inevitable haze these old lenses keep inside.

suggestions are very welcome!

regards, michael
 
I think "discretion is the better part of valor" (and value), so I'm gonna pass on the cheap lens w/ the certain high cost of polishing and uncertain results.

Thanks for the comments, guys.
 
Help to reassemble iris blades on Summar

Help to reassemble iris blades on Summar

I need to know how to keep all the 12 iris blades on my 1937 Summar aligned so I can reassemble the darn thing. I can get close, but in the last steps I cannot get all the inner blade knobs into their holes while keeping all the outer blade knobs in their slots.
If I had not tried to disassemble it to re-align the aperture ring, things would have been ok. As it turns out, it cannot be made to align with the index mark because the front and rear element groups must be from more than one lens. Some previous owner took two bad lenses and made one good one, it appears, by simply unscrewing the front group and putting it into the body of a different Summar. It works ok other than not lining up with the aperture index mark.
 
There's an article on CRR Luton's site about how they re-polish a Summar. But it's almost certainly not cost-effective.

If you re-polish a rangefinder lens such that it's focal length changes, re-collimation may not be all it needs. If it changes focal length enough, you need a different focusing mount, they are made with different pitches on the RF cam for different ranges of focal length.

Arax may still be able to re-polish a lens, but they are out of the coating business. (The local factory with a lens coating machine shut down, or something like that.)

Assembling iris blades takes great dexterity and the patience of a saint. I've done it on my Summar, it wasn't fun, I don't want to do it again.
 
Summar Blades

Summar Blades

I can get all the blades in the lens body with their knobs in the lower holes, but can't seem to get the control ring onto the upper knobs without knocking the lower knobs out. The lower knob holes are obscured by the control ring.
I can imagine the factory had an aligning jig, but to make a jig to align the top knobs on the blades would be a major task.
I suppose you just aligned your blades meticulously and set the control ring down on them with great care and much adjusting of the blade position with a pick?
It takes a lot of patience, for sure, but it seems like their should be a technique to doing it than I am missing.
 
Several of my friends had this done in the 70s. The general consensus was that the lens was never quite the same afterwards, though I do not know how far they were seeing what they expected to see. Some had their Summars coated, and reckoned that they were fascinating once they'd done so. Optical Instruments (Balham) can do it, but as far as I recall, they're not cheap.

Incidentally, it is my understanding that when you repolish any lens, coated or not, you also remove some of the glass.

Cheers,

R.
 
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I've sent a lens for repolishing to one of the last french man that has special tools to do it. He is 84 years old. He does this since 64 years. He has special calibrated optical profile that keeps optical formula at their best point after repolishing. He has some for summicron or other Leitz and Rolleiflex lenses.

The basic optical formula will not be affected in tremendous point. There are a lot of vintage summicrons that are very good, that have been 1 or 2 times repolished, but you don't know it !

I have sold cameras that had repolished lenses, and the owners were absolutely stunned by the results on film.

10% loss of resolution is a detail while picture taking. When it is well done, it is far better than a scratched lens.
 
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Summar Iris Diaphragm

Summar Iris Diaphragm

John Shriver said:
I do know that you want all the blades on the "open" position when you put in the control ring. That's the only setting where you can have them all in the "same" position.
Click to expand...

Thanks for that insight, that is the way I have been trying it.
Same difficulties still encountered. Just can't get the last blade to fall into place without gradually dislodging the rest.
Next step is that I have scribe marked all the locations of the lower base knob holes so I can determine the correct positions since one can't view the knobs and the holes themselves once the blades are layed-in.
I am using some BMW super high impact grease now to help hold the blade base knobs in their holes. This grease is very sticky and is supposed to be completely immobile and will not migrate even under high temperatures. It has the consistency of hot mozarella cheese and will string out several feet, spider-web thin, if pulled.
In the process I have dislodged most of the ink at the edge of the front group and will need to re-paint the edge. Any suggestions on that re-inking process?
I feel the lens re-assembly fairies to be on my side and feel FORCE to be strong in me, now and will confidently and with new resolve, try again.
 
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