Summicron Collapsible focus issue
Old 6 Days Ago   #1
LCSmith
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Summicron Collapsible focus issue

A beautiful Summicron collapsible came in the mail recently from a US Leica dealer. The optics look brand new. Everything about the lens is immaculate.

The only problem is that it seems to back-focus significantly when focusing with the RF. At minimum focus distance the disparity is about 2 or 3 inches. When focusing in "live view" on my M-P the lens makes very sharp, contrasty images. But I do not use live view.

Is there a fix?

I should say also that the RF on my M-P is aligned properly.
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Old 6 Days Ago   #2
Benjamin Marks
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Send it back. If your camera focuses with other lenses, it is possible that the mount is attached incorrectly or there is some other problem with the position of the focus cam. In either event, this should not be your problem.
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Old 6 Days Ago   #3
LCSmith
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Quote:
Originally Posted by Benjamin Marks View Post
Send it back. If your camera focuses with other lenses, it is possible that the mount is attached incorrectly or there is some other problem with the position of the focus cam. In either event, this should not be your problem.
Yes, this is my inclination.

It baffles me that the lens wasn't checked properly before being sold.

I did contact the dealer as soon as I received the lens. The dealer indicated that this was a common problem with old lenses and "was part of their character"
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Old 6 Days Ago   #4
Benjamin Marks
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The dealer's response is rank balderdash. If I were the dealer, I'd be embarrassed to utter those words. It is true that some designs do have a bit of backfocus, but they tend to be the faster lenses. My thoroughly modern 50 f:1.5 Sonnar comes to mind. But Leica has had the ability to manufacture a well-corrected 50 f:2 lens since the 1930's. Call him on it.
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Old 6 Days Ago   #5
LCSmith
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Quote:
Originally Posted by Benjamin Marks View Post
The dealer's response is rank balderdash. If I were the dealer, I'd be embarrassed to utter those words. It is true that some designs do have a bit of backfocus, but they tend to be the faster lenses. My thoroughly modern 50 f:1.5 Sonnar comes to mind. But Leica has had the ability to manufacture a well-corrected 50 f:2 lens since the 1930's. Call him on it.
This was my feeling also. I wonder whether the dealer's hope was that the lens would be used on a non-rf camera and therefore its flaw might go unnoticed.
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Old 6 Days Ago   #6
jszokoli
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Maybe float the idea that the dealer would refund the cost of the repair? Send it off for an estimate and see if it can be fixed...


Likely the reason it looks unused is that it was unused due to this issue.
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Old 5 Days Ago   #7
nickthetasmaniac
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Quote:
Originally Posted by LCSmith View Post
I did contact the dealer as soon as I received the lens. The dealer indicated that this was a common problem with old lenses and "was part of their character"
Bollocks. I'd be sending it back and finding a new dealer.
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Old 5 Days Ago   #8
TenEleven
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Quote:
Originally Posted by LCSmith View Post
This was my feeling also. I wonder whether the dealer's hope was that the lens would be used on a non-rf camera and therefore its flaw might go unnoticed.
It might show up less on film. Even with a known good lens, critical focus is hard to achieve on a digital Leica using only the RF.

That said the extent of back focus seems to be rather large. Does it make a sharp image at infinity with focuse set to the hard infinity stop when pointed at a far away landscape? (100ft or more)

It doesn't: Someone, likely when cleaning the lens, moved the lens elements out of proper adjustment.

It does: The lenses focus cam is off. It might also be a compounded tolerance issue of the lens being a bit off and your M-P also being a bit off.
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Old 5 Days Ago   #9
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If it has 2~3" of back focus that isn't back focus. It would be bad on a film camera also. Tough to image what could be wrong with the lens.
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Old 5 Days Ago   #10
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Here's a dissenting opinion. From your description, it sounds too nice to give it up. A collapsible in that condition is a rare find. It may be that the helicoid was assembled incorrectly during servicing. You might consider sending it to YYE (or other good tech) to see if it can be corrected. It's a great lens!
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Old 5 Days Ago   #11
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Give the seller a chance to make it right on the price and send it to DAG.

He has the proper collimators & magnification optics, lenses made of
tool steel by Leitz, infinity targets, 1 meter test stand & 45 years of
adjusting Leica R/Fs.

No one else has all this, with the possible exception of Leica...
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Old 5 Days Ago   #12
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Thanks everyone very much for your generous responses. Indeed the coatings are like new and the lens is very smooth, so I tried it on my M4 and ... the focus seems to be spot on.

This baffles me. I have never had difficulty nailing focus with a 50/2 on a digital M, not even with my old Summitar. I guess this means the collapsible prefers to remain analog.

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Old 5 Days Ago   #13
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Quote:
Originally Posted by Rob-F View Post
Here's a dissenting opinion. From your description, it sounds too nice to give it up. A collapsible in that condition is a rare find. It may be that the helicoid was assembled incorrectly during servicing. You might consider sending it to YYE (or other good tech) to see if it can be corrected. It's a great lens!
My thoughts also. Good suggestion. Not sure if it needs cleaning but Youxin dismantled my Collapsible Summicron. Cleaned the elements and lubed the helical. Did a great job.

Might be worth have him inspect it.
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Old 5 Days Ago   #14
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I sold for an authorized Leica dealer when the M9 was released. I would send newly sold customer bodies and lenses straight to DAG for focus calibration (before the customer took delivery, in fact) as we had many customers that reported focus problems.

To clarify: brand new, out of the box gear...that did not focus accurately.

Digital is much less forgiving than analog when it comes to nailing focus at the sensor plane.

If it were me, I'd do the same exact thing in this case...send body and lens to DAG for calibration.

Back in those days he'd turn it around in a couple of days, call him for his current lead time.
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Old 5 Days Ago   #15
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Splitimageview's recommendation is sound. The likelihood of finding a mint Summicron that doesn't need service is very low unless you pay a very high price for the replacement.
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Old 2 Days Ago   #16
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There is what splitimageview said. There's also the caveat that with film there's always going to be a slight bow in the focal plane (away from the lens) which the lens and camera designers were aware of and designed for. It's why they tried glass pressure plates, vacuum backs and other tricks late in the film game.

This means that sometimes on digital where the sensor and the focal plane is completely flat, lenses don't always perfectly hit the same focus. There's also a raft of other potential pitfalls that I won't go into here.
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Old 2 Days Ago   #17
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It could be that the lens is just slightly off one way and your rangefinder on the digital M the other. You could always send both to DAG and have them adjusted to work with each other better.
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