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Apo Summicron 75mm Focusing Problem


SmokeSolid

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Hi,

Just wondering about a problem with my Apo Summicron 75m.

It has always been a nightmare to focus but this was on my side.

Suddenly after my last trip 3 months ago I noticed that focusing with the Optical Viewfinder didn’t hit focus.

Just with live view it hit it perfectly I really don’t like using the live view to focus unless it’s necessary.

Its of focus just a tad can this be fixed with out sending it in in my part of the world I don’t have any Leica technician close and during Covid for me is imposible to send it.

Let me know please if any had experienced something like this before on this lens.

Best,

J

 

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A little more detail on exactly how it is mis-focusing (front? back? Both, at opposite ends of the focus scale?) would help.

However, the 75 ASMA (APO-Summicron-M-ASPH) has had a little history of focus-adjustment problems throughout its life. I have had an example that, using the RF, back-focused ("beyond infinity") at long distances and front-focused in the close-up range. And run across several that were just "off" everywhere, or acquired significant abnormal aberrations (blurry corners and excess color fringing) at certain distances.

My personal theory is that the floating elements, with their own additional focus movement, just sometimes get out of whack with the overall focusing movement.

The lens, even when working correctly, is subtly changing the optical formula (spacing of the elements) as it focuses. And if that gets out of tune, especially using a proxy focus system (the rangefinder) rather then through-the-lens, the lens no longer tracks the RF correctly - it is "the wrong" formula at certain points. It is no longer exactly the lens Peter Karbe designed.

The very first 75 ASMA I bought back in 2005 worked perfectly. Then I sold it - and it took me about 10 years to find a used one that worked as flawlessly.

It's worth noting that Leica has never attempted to upgrade the 90 ASMA or 135 APO to an FLE construction - just a bridge too far for a fast long lens with a rangefinder instead of a focus screen.

Now, age of the lens may be a factor. Not only would an older lens have had more opportunity to drift in adjustment over time, but with Leica's move to the new factory in Wetzlar, supposedly the current lenses are now built to even tighter tolerances.

(BTW - I charge a licensing fee for using the "bearded guy with a Leica" avatar image. ;) Welcome to the forum!)

 

Edited by adan
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First issue is whether it is your rangefinder or the lens that is at fault. If you have other M lenses that are not a problem, then it is probably the 75 itself. You can adjust the RF yourself, but a lens needs a return to Wetzlar. The only time my 75 went out of focus was when I threw it on the cobbles outside Parma cathedral (shocking quality - what were Leica thinking of 😉). Other than that it has always been fine. My 90AA needed recalibrated twice though.

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39 minutes ago, adan said:

However, the 75 ASMA (APO-Summicron-M-ASPH) has had a little history of focus-adjustment problems

That's is very true, so does the 90APO.

Some say, which I also agree, send the camera and lenses for adjustment separately.  NJ office screwed all my lenses to fit a bad body.  Then replace a new body, all lenses are off.  It took 2+ years in total to undo their damage.  I am still pissed today.

 

 

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One other thought. With shorter focal length lenses you may be saved by DOF, whereas at 75mm exact focus becomes more critical. Is your eyeglasses prescription up to date? Over the years when I swore at my M bodies and wasn't getting on the spot focus with longer lenses, it was usually that I needed a tweak in my eyeglasses prescription.

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I have owned 2 x 75 Summicrons. The first was way off and I gave up on it. The second was fine. I eventually decided I didn't like get on with this lens and I no longer own it. To me the Summilux is far pleasanter to use but not as optically perfect - I'm happy to live with its slight imperfections though.

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Hi Adan,

Thanks for taking the time to reply.

The spacing of the elements and the change in optical formula sound extremely interesting and possible of course. Ill look into it.

Regarding the lens:

It’s a  front focus issue. 
Lens has around 5 years. 
I just shot the corner of my TV and it seems in focus to me through the viewfinder at 1.30Meters

Its in real focus at 1.6Meters.

Extremely annoying and I really love the lens but somehow its of focus permanently.

Best,

J

 

 

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4 hours ago, LocalHero1953 said:

First issue is whether it is your rangefinder or the lens that is at fault. If you have other M lenses that are not a problem, then it is probably the 75 itself. You can adjust the RF yourself, but a lens needs a return to Wetzlar. The only time my 75 went out of focus was when I threw it on the cobbles outside Parma cathedral (shocking quality - what were Leica thinking of 😉). Other than that it has always been fine. My 90AA needed recalibrated twice though.

Hi LocalHero,

Thanks for replying.

When I used it on my M240 same thing.

The camera issue is discarded had a recent Leica Service tried a 90 and was perfect and all my wides so, its the lens for sure.

At least I can use it with live view. :)

Seems like its a common issue at least.

Best,

J

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3 hours ago, jaeger said:

That's is very true, so does the 90APO.

Some say, which I also agree, send the camera and lenses for adjustment separately.  NJ office screwed all my lenses to fit a bad body.  Then replace a new body, all lenses are off.  It took 2+ years in total to undo their damage.  I am still pissed today.

 

 

I would of have gone insane. Yea better sometimes is to work around the problem. At least for model+tripod stuff I don’t mind. For street portraiture witch I love its scary bc to much to think about with the live view on I don’t like to use the screen other than for reviewing some shots.

Hope you and your gear are great.

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2 hours ago, spydrxx said:

One other thought. With shorter focal length lenses you may be saved by DOF, whereas at 75mm exact focus becomes more critical. Is your eyeglasses prescription up to date? Over the years when I swore at my M bodies and wasn't getting on the spot focus with longer lenses, it was usually that I needed a tweak in my eyeglasses prescription.

Hi Spydrxx,

I use glasses but I’m not that blind I can shoot with out them too.

Should be a screw to calibrate the lens and make it easy :)

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2 hours ago, pgk said:

I have owned 2 x 75 Summicrons. The first was way off and I gave up on it. The second was fine. I eventually decided I didn't like get on with this lens and I no longer own it. To me the Summilux is far pleasanter to use but not as optically perfect - I'm happy to live with its slight imperfections though.

I see they came with problems straight out of the factory, I usually don’t mind sharpness and its not a decisive factor for me. But in this case is what I like and its just like a 50 almost. If i get bored ill fix it and sell it for a 90.

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How is the focus at infinity?

Set the focus ring to the hard stop at infinity and aim at something at least 1/2 mile /1 km away. Do the RF images align perfectly (they should), or do you see a double-image in the RF patch? Take a picture of that distant object - is it sharp or fuzzy at that focus setting?

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I don't get the impression the 75 is any worse than other longer, wider M lenses, where it is noticeable because of the shallow DoF. As I wrote earlier, my particular problems were with the 90 not the 75. Of course, if you post a thread about any single lens, everyone reports on the problems they've had with that lens, and it gets a reputation for being a 'problem' lens😉.

I can't answer for Leica US, but Wetzlar say they calibrate lenses and bodies to independent standards, not to match each other. So you should not have to send the lens and body together for recalibration. On one occasion Leica in London asked to see both body and lens so they could check themselves which had to go for recalibration to Wetzlar - on that occasion only the body was sent.

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1 hour ago, LocalHero1953 said:

I don't get the impression the 75 is any worse than other longer, wider M lenses, where it is noticeable because of the shallow DoF. As I wrote earlier, my particular problems were with the 90 not the 75. Of course, if you post a thread about any single lens, everyone reports on the problems they've had with that lens, and it gets a reputation for being a 'problem' lens😉.

I can't answer for Leica US, but Wetzlar say they calibrate lenses and bodies to independent standards, not to match each other. So you should not have to send the lens and body together for recalibration. On one occasion Leica in London asked to see both body and lens so they could check themselves which had to go for recalibration to Wetzlar - on that occasion only the body was sent.

There was a time when there were quite a few queries here on LUF bout this lens and its focus problems. They seem to me to have mostly stopped which leads me to wonder whether a mix of factors may have been involved. The lens dates from 2005 so a few may well have had issues due to lack of use or heavy use. The double mechanical mechanism clearly must need greater care in assembly/adjustment than a simple, single helicoid. At 75mm f/2 is demanding on an RF as are longer/faster lenses. So adjustment/callibration has to be absolute in order for them to work as they should. It may now be that earlier lenses are mostly well adjusted after having been back to Leica, and later copies were tested more rigorously during assembly? 

Digital cameras, as we well know, are demanding on lenses especially if their users are critical of their results. My second copy was capable of really stunning results but somehow it never gelled with me whilst the Summilux does.

Lastly, since the OP lens went from being ok to not, I'd suggest that something needs adjustment. If it was mine I would send it in to Leica to get it sorted out. If the results are good using the EVF its most likely that the RF cam has gone out of adjustment. If the lens is not producing images which are as good as it did previously, its something else.

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9 minutes ago, pgk said:

There was a time when there were quite a few queries here on LUF bout this lens and its focus problems. They seem to me to have mostly stopped which leads me to wonder whether a mix of factors may have been involved. The lens dates from 2005 so a few may well have had issues due to lack of use or heavy use. The double mechanical mechanism clearly must need greater care in assembly/adjustment than a simple, single helicoid. At 75mm f/2 is demanding on an RF as are longer/faster lenses. So adjustment/callibration has to be absolute in order for them to work as they should. It may now be that earlier lenses are mostly well adjusted after having been back to Leica, and later copies were tested more rigorously during assembly? 

Digital cameras, as we well know, are demanding on lenses especially if their users are critical of their results. My second copy was capable of really stunning results but somehow it never gelled with me whilst the Summilux does.

Lastly, since the OP lens went from being ok to not, I'd suggest that something needs adjustment. If it was mine I would send it in to Leica to get it sorted out. If the results are good using the EVF its most likely that the RF cam has gone out of adjustment. If the lens is not producing images which are as good as it did previously, its something else.

Related to the floating element is the fact that this lens has an unusually close focus, so at f/2 you notice focusing errors very quickly.

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