75mm Summilux back focusing

[evikne]

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I have recently purchased a used 75mm Summilux f/1.4 which has an issue with back focusing. I did some tests today, and from minimum focusing distance to about 1.5 meters, the focus is very good. Then the back focusing is more and more visible at longer distances. At 2 meters the focus is about 5 cm behind, and at 3 meters it back focuses maybe 30 cm. I can't see any difference at different apertures.

 

What is the best thing to do? Send it to Leica for an adjustment? Do they need the camera as well? (hope not). Or should I just find a way to live with it, e.g. try to remember how much nearer I have to focus at different distances?

 

I have planned to buy a Visoflex, but currently I can't afford it.

Edited November 30, 2017 by evikne

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[pgk]

I bought one with severe focus problems on the basis that it would go to Leica to be sorted (and code) which it did. It is now absolutely fine and I'm the only focus problem it has. So all I can say is that Leica fully sorted my copy out and did a great job. They shouldn't need your camera unless it has focus issues with other lenses.

[Maarten]

When focus is good at short distance and backfocus increases with distance then usually the viewfinder alignment at infinity is the culprit.

 

I would start checking alignment in the viewfinder with the lens at infinity. Take a test object at a distance of at least 1 km, preferably in good weather conditions.

There are two conditions possible:

- When the viewfinder is not at infinity while the lens is, you use the 2mm hex key to align infinity. Usually this solves the issue

- If this is not the case and the viewfinder is aligned with the lens at infinity, the lens needs to be calibrated by Leica

 

This test has worked for me over the last 10 years!

Sometimes the lens was at fault, but most times the viewfinder had drifted somewhat.

 

Maarten

[DickieT]

I would definitely have it fixed - it is a wonderful lens that is hard enough to focus without these issues ! Is there no good repair location in Norway ? If the viewfinder needs alignment with the lens they need both..

Edited November 30, 2017 by DickieT

[SilentShutter]

When focus is good at short distance and backfocus increases with distance then usually the viewfinder alignment at infinity is the culprit.

 

I would start checking alignment in the viewfinder with the lens at infinity. Take a test object at a distance of at least 1 km, preferably in good weather conditions.

There are two conditions possible:

- When the viewfinder is not at infinity while the lens is, you use the 2mm hex key to align infinity. Usually this solves the issue

- If this is not the case and the viewfinder is aligned with the lens at infinity, the lens needs to be calibrated by Leica

 

This test has worked for me over the last 10 years!

Sometimes the lens was at fault, but most times the viewfinder had drifted somewhat.

 

Maarten

 

Great advice - thank you !  

[evikne]

When focus is good at short distance and backfocus increases with distance then usually the viewfinder alignment at infinity is the culprit.

 

I would start checking alignment in the viewfinder with the lens at infinity. Take a test object at a distance of at least 1 km, preferably in good weather conditions.

There are two conditions possible:

- When the viewfinder is not at infinity while the lens is, you use the 2mm hex key to align infinity. Usually this solves the issue

- If this is not the case and the viewfinder is aligned with the lens at infinity, the lens needs to be calibrated by Leica

 

This test has worked for me over the last 10 years!

Sometimes the lens was at fault, but most times the viewfinder had drifted somewhat.

 

Maarten

 

Thanks for the advice! I can make a test tomorrow when the daylight is back.

 

But I have other, newer lenses that focuses perfectly at all distances, so I don't think my viewfinder can be the problem.

Edited November 30, 2017 by evikne

[JWW]

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When I bought the 75mm Summilux way back in the M8 days, it too was off focus.   In the USA, I sent DAG the lens and he fixed it perfectly and focus is still correct on my M10. 

[M10Alpine]

How much is a LUX 75mm in good condition?

[evikne]

How much is a LUX 75mm in good condition?

 

About 4000 USD I think. 

[bencychin]

How much is a LUX 75mm in good condition?

I just acquired a late version of Lux 75 for $3,650 including original box.

Everything is mint condition as described, Only snag is the foam in the box needs to be discarded as it had chemically decomposed.

 

Starting to learn the ropes to use its strength.

[69xchange]

Got a 75mm lux (1st version) as well and having this issue. @evikne, was this problem ever fixed when sent to leica? If so, what was the cost and how did they fix it? Thanks!

[evikne]

1 hour ago, 69xchange said:

Got a 75mm lux (1st version) as well and having this issue. @evikne, was this problem ever fixed when sent to leica? If so, what was the cost and how did they fix it? Thanks!

Yes, after the fourth (!) submission to Wetzlar, the focus was absolutely perfect. I only paid for the first submission (about US$217 at the time), the others were free. I told them that I wanted to use the lens mostly wide open, at typical portrait distance. All in all, it took about a year, because I also kept it for a bit every time I got it back, to try it out. 

The tragedy was that shortly after I finally got a lens that worked perfectly, I had to sell it again because I needed money for something else.

[Roland Rick]

On 11/30/2017 at 4:26 PM, evikne said:

I have recently purchased a used 75mm Summilux f/1.4 which has an issue with back focusing. I did some tests today, and from minimum focusing distance to about 1.5 meters, the focus is very good. Then the back focusing is more and more visible at longer distances. At 2 meters the focus is about 5 cm behind, and at 3 meters it back focuses maybe 30 cm. I can't see any difference at different apertures.

 

What is the best thing to do? Send it to Leica for an adjustment? Do they need the camera as well? (hope not). Or should I just find a way to live with it, e.g. try to remember how much nearer I have to focus at different distances?

 

I have planned to buy a Visoflex, but currently I can't afford it.

That's very interesting, I got one last Saturday (Feb 8th 2025), version 2 fro 1983.

The optics are so far OK, the lens was already bit coded by it's pre-owner and the range finder mechanism is accurate. I tested it on my M11M.

But it has a similar but slightly different issue, it's only a problem wide open at 1.4, stopped down to 2 it's almost gone but you lose the vignetting and swirly bokeh effect and it becomes very sharp.

But then I could use the APO-Summicron-M 2/75 or my APO-Summicron-SL 2/75 also.

Problem description: If the subject is in a range between  about 1.8 and 3.8 (educated guess) metres, I can focus perfectly and the lens does what I expect to do from a portrait lens.

Other than that - subject closers or farther - the subject gets a dramatic halo, a little bit would be fine but not that much. Being lack of models, I used two wooden poles to show you what I'm talking about, I won't win a price with it, but it explains the issue.

Has someone an idea what's possibly the issue? The lens looks very well for a 42 years old lens and the optics are basically find except for that glow I personally don't like. Other than that, David Hamilton would have been lucky to own it.

Appreciate any reply.

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[lct]

Can be seen on out of focus subjects at full aperture, on closeups too. Crop at f/1.4 here.

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