inconsistent focus depending on focus direction

[mikelevitt]

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On 9/20/2022 at 8:26 AM, hmzimelka said:

So it took the Nokton 75mm f/1.5 to raise this issue, which kept me busy for a few days figuring out a focus inconsistency I was having with it.

Initially, I chalked it up to the narrow DOF and the lens' ridiculously short focus throw. 

Basically, what turns out to be consistently the case, is that pulling focus from infinity to my subject will result in perfect focus.
However, pulling focus from close focus to my subject will consistently result in a back focus. 

Now this has never been noticeable until the the Nokton 75mm came along. But now that I'm looking for the behaviour, I'm finding it with my Summicron and Ultron 28mm ASPH too, but with these two the difference is small. 

What bothers me is that this is 100% reproducible with my camera with any of these three lenses. If I focus on my subject from infinity, and repeat this multiple times, the focus always falls on the same spot. Taking multiple images but with each shot pulling focusing from close focus, the images are also all focused on the same spot but slightly behind the subject.

Now I cannot figure how this can be a rangefinder issue since I cannot discern any lag or slop on the rangefinder patch. It is responsive to even the slightest of lens inputs. But I don't see how its a lens issue either as there is also no slop there. I initially thought it could be the 75mm Nokton since a tiny amount of slop in the helicoid could have the focus ring move but not engage the optical block since the focus throw is so very short.

 

Now I'm sitting with a Nokton 75/1.5 thats arguably unusable. I'm not sure if my M11 is faulty, and I'm 11000km from the nearest Leica service centre so I can't just send it off to be checked. 

 

The problem with your methodology is that it is unscientific.  Reproducing this with 3 different lenses would suggest a camera problem.  But your "testing" depends on your own ability to focus a rangefinder - which under the best of circumstances is not 100% dependable.  

 

Try downloading and printing a test chart and using a tripod, focusing carefully on a vertical line on the chart, and comparing to live view as you go.  

 

Rangefinder focusing is inconsistent.  If you want it to be exact, use the EVF...

[hmzimelka]

2 hours ago, mikelevitt said:

The problem with your methodology is that it is unscientific.  Reproducing this with 3 different lenses would suggest a camera problem.  But your "testing" depends on your own ability to focus a rangefinder - which under the best of circumstances is not 100% dependable.  

 

Try downloading and printing a test chart and using a tripod, focusing carefully on a vertical line on the chart, and comparing to live view as you go.  

 

Rangefinder focusing is inconsistent.  If you want it to be exact, use the EVF...

I have tested it across a few lenses now; Hektor 13.5cm. Nokton 75/1.5. Summicron 50 V. Summicron 5cm Collapsible. Ultron 28/2 ASPH II.

The error is large with the 75/1.5 and the 135mm lens. As mentioned, at 2m, the delta between focusing from either direction is just over 40mm. This is also a consistent distance every time.

I have also mentioned that the results, ie the subject focus, is consistently the same if focused from the one direction, landing always on the same spot. Repeatable.

While I didn't print a test target, I have used B&W text as a target and a tripod. 

 

Edited September 22, 2022 by hmzimelka

[jdlaing]

Please don’t take this as an indictment. It is not meant to be derogatory towards you in any way but only to help.

I vote for user error with a slight edge toward the mechanics of how a rangefinder lens works. If your largest error is with long lenses that would confirm it for me. The next step would be to contact Leica. Just don’t bring up Norton and Ultron as they could care less how those work on a Leica body. I doubt very seriously that it is the camera causing your problems.

[hmzimelka]

7 hours ago, jdlaing said:

Please don’t take this as an indictment. It is not meant to be derogatory towards you in any way but only to help.

I vote for user error with a slight edge toward the mechanics of how a rangefinder lens works. If your largest error is with long lenses that would confirm it for me. The next step would be to contact Leica. Just don’t bring up Norton and Ultron as they could care less how those work on a Leica body. I doubt very seriously that it is the camera causing your problems.

I understand. No offence taken. Its obviously a valid point.

However, hear me out on this. If I focus the long lenses, or any lenses for that matter, from one direction only, the focus is always spot on. Completely repeatable, and if there is any variation, that is user error. Changing this direction of focus, over multiple images on the same subject, every image is consistently back focused at the same place again. The back focus with the 75mm is just over 4cm at a 2m focus distance. Thats huge.

If images the images produced from each direction are that consistent with each other across several repetitions, then it can't be user error. User error would show itself producing varying focus points when testing the repeatability of each focus direction.

Unfortunately if this is a camera issue, I will be selling the M11. I've just had about enough issues with Leica since last November when I ordered my M10M to now. 

M10M was faulty, and now I'm on my fourth M11 body. I've lost significant amounts of money on import taxes for the M10M and Summicron 35mm ASPH that I can't get back for those two faulty items that were returned. I've been far too patient with Leica for the issues experienced with them, just for the sake of really just wanting a rangefinder camera again. But I'm over it.

Edited September 23, 2022 by hmzimelka

[Photoworks]

7 hours ago, hmzimelka said:

I understand. No offence taken. Its obviously a valid point.

However, hear me out on this. If I focus the long lenses, or any lenses for that matter, from one direction only, the focus is always spot on. Completely repeatable, and if there is any variation, that is user error. Changing this direction of focus, over multiple images on the same subject, every image is consistently back focused at the same place again. The back focus with the 75mm is just over 4cm at a 2m focus distance. Thats huge.

If images the images produced from each direction are that consistent with each other across several repetitions, then it can't be user error. User error would show itself producing varying focus points when testing the repeatability of each focus direction.

Unfortunately if this is a camera issue, I will be selling the M11. I've just had about enough issues with Leica since last November when I ordered my M10M to now. 

M10M was faulty, and now I'm on my fourth M11 body. I've lost significant amounts of money on import taxes for the M10M and Summicron 35mm ASPH that I can't get back for those two faulty items that were returned. I've been far too patient with Leica for the issues experienced with them, just for the sake of really just wanting a rangefinder camera again. But I'm over it.

did you address it with Leica support? it would be interesting it is a viable issue.

I will try some tests here to see if it every camera

[hmzimelka]

19 hours ago, Photoworks said:

did you address it with Leica support? it would be interesting it is a viable issue.

I will try some tests here to see if it every camera

Not yet. Not sure I'm even keen on sending the camera across 3 countries and 11000km to Leica for an unknown but lengthy time just for Leica to return it and say it's within spec. Just like with the sensor bifurcation issue I had with the M10M where Leica were completely unwilling to help. 
 

So in that light I'm not confident and rather pessimistic about sending it to Leica. 

Edited September 24, 2022 by hmzimelka

[lct]

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Not sure i would send the body in if the lens is the culprit. Should be easy to check with an EVF normally so i would try an electronic Visoflex in a Leica store of your country if i were in your shoes. Now i realize i am 10,000 km away from Namibya so it is just an idea FWIW .

[silverimage]

On 9/22/2022 at 2:57 AM, hmzimelka said:

Is there any chance the camera rangefinder system can contribute to this error? There are series of linkages but I don't know much about the rangefinder mechanism to understand where this kind of error can come from. After all, only the the arm is sprung or has tension, and not necessarily the rest of the system that relies on gears?, bushes?,  etc

 

Anyways. With the Nokton 75mm f/1.5, the focus error is around 40mm at a focus distance of 2 meters.

If I set my camera on a tripod and land the focus position on the exact same mark, the the best of my ability, I get consistently accurate focus no matter the directions with little to no error. So either the RF helical is causing the issue or the camera's rangefinder mechanism.

Here are two images followed by crops of the same images. First, focus direction from infinity to subject. Second, focus from close focus to subject.

M11, with Nokton 75mm at f/1.5.

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This just feels like an overly large error and I'm concerned my camera is part of, or largely the issue... unfortunately I don't have access to another M camera.

 

 

I too have the 75/1.4 Nokton and it really frustrated me to come up with an image in focus. Eventually I purchased the Visoflex-2. I know it takes away from the rangefinder experience? Well my older eyes are enjoying an amazing lens on an amazing M11 all that more. I can hit focus; sometimes with the rangefinder, just not wide open. The EVF also opened up the use of my extensive Nikon-F manual lens collection with an adapter. My Leica lenses focus without issue. Now, if I could keep the M11 from freezing up?

[hmzimelka]

Im fortunate to have good eyesight. No problem focusing the rangefinder and have pretty excellent success rate nailing focus as long as the focus direction is from infinity. 
 

But I suspect things are getting worse. I'm visiting family in inland Namibia and it's 36°C here... the issue seems to be getting worse. I'm getting a front focus with my summicron 50mm now from infinity and a back focus from close focus. This has never been like this before and it's not the first time I've been in warm weather with the camera. 

I'll be writing Leica and returning the camera at some point to the dealer for an inspection and repair by Leica. Depending on the outcome I'll see when I'll sell the camera. I don't have much faith left in Leica. 

Edited September 24, 2022 by hmzimelka

[FlashGordonPhotography]

It has a name.

Gear lash.

It's the mechanical delay between one cog moving and engaging the next one. All mechanical lenses have it to a tiny extent otherwise the tollerances would be so tight the cogs couldn't move with one another at all. In most modern lenses it's hidden within the range of DoF.

More common to be an actual issue in older lenses and less in modern ones due to improved manufacturing tolerances. Can be exaggerated if the lens also has focus shift or there are issues with the RF mechanism being sloppy as well.

On modern Leica lenses it's most often seen on the 135APO. 

There could be an RF issue but it's extremely unlikely to be only an RF issue.

Gordon

[jankap]

21 hours ago, hmzimelka said:

I'll be writing Leica and returning the camera at some point to the dealer for an inspection and repair by Leica. 

The 75mm is a Voigtlander?

I suppose, the Hektor does not have a ring connecting to the focussing mechanism, but a rod. That means, that there is a mechanism from turning to moving inside the lens. 

[davidmknoble]

Just a note, and maybe not significant, but I see that of all the lenses you tested, only one was a current leica lens (the Summicron 50 V).  It is hard to blame Leica if non-leica lenses are having trouble with a mechanical rangefinder system.  The level of mechanical tolerance on a Lecia M lens is much more than the acceptable tolerance for other brands.  It is one of the reasons the lenses cost more (glass and design as well). I realize the 5cm collapsable was made by Lecia, but it was made with a film tolerance, not digital and is old enough that it may not be in tolerance today anyway.

So, I am not as apt to suggest the m11 is a fault without more testing of lenses made by the company that designed the system.

Just my 2 cents… I know it is frustrating.  I have never been able to accurately focus the 90APO summicron at f/2 in mid distances wtihout an EVF.  At infinity no trouble and at f/4 or f/5.6, no problem.  

[hmzimelka]

7 hours ago, davidmknoble said:

Just a note, and maybe not significant, but I see that of all the lenses you tested, only one was a current leica lens (the Summicron 50 V).  It is hard to blame Leica if non-leica lenses are having trouble with a mechanical rangefinder system.  The level of mechanical tolerance on a Lecia M lens is much more than the acceptable tolerance for other brands.  It is one of the reasons the lenses cost more (glass and design as well). I realize the 5cm collapsable was made by Lecia, but it was made with a film tolerance, not digital and is old enough that it may not be in tolerance today anyway.

So, I am not as apt to suggest the m11 is a fault without more testing of lenses made by the company that designed the system.

Just my 2 cents… I know it is frustrating.  I have never been able to accurately focus the 90APO summicron at f/2 in mid distances wtihout an EVF.  At infinity no trouble and at f/4 or f/5.6, no problem.  

It's quite a stretch to imply that Voigtlander has lesser tolerances than Leica. I guess you haven't seen my comments in this thread describing my various issues with Leica lenses. I have had several bad experiences with new Leica lenses that were faulty. Of the last Leica lenses I tested a month ago was an APO 75mm and this thing had such strong front focus that it couldn't reach subject sharpness at f/8, not to mention infinity hard stop was a soft mess at the lens hard stop with rangefinder patch alignment for infinity.

I will choose Voigtlander quality assurance over Leica any day, since my experience across something like 7 new Leica lenses, not to mention the various M11 and M10M bodies I've gone through, is that Leica's QC has let me down and cost me significant money. 

 

[hmzimelka]

On 9/25/2022 at 7:08 AM, FlashGordonPhotography said:

It has a name.

Gear lash.

It's the mechanical delay between one cog moving and engaging the next one. All mechanical lenses have it to a tiny extent otherwise the tollerances would be so tight the cogs couldn't move with one another at all. In most modern lenses it's hidden within the range of DoF.

More common to be an actual issue in older lenses and less in modern ones due to improved manufacturing tolerances. Can be exaggerated if the lens also has focus shift or there are issues with the RF mechanism being sloppy as well.

On modern Leica lenses it's most often seen on the 135APO. 

There could be an RF issue but it's extremely unlikely to be only an RF issue.

Gordon

Yes, this gear lash is somewhat easily tested when focusing the lens from infinity to a specific mark/position on the lens barrel and then comparing that image to one where the focus was achieved from the other direction. For the Nokton 75mm there is a difference but its very very little, far too little to bother me. With the Summicron 50mm its really not applicable. With the Hektor 13.5cm, there is a little too, but its too small to bother me.

Focusing the M3 with the Nokton 75mm f/1.4 from both directions results in a focus position on the lens barrel that is pretty much always the same no matter the direction. On my M11, the difference in focus ring position is quite large. Almost as wide as one of the DOF scale lines at a distance between 3-5 meter focus distance. 

The issue seems to be getting worse on the M11. As mentioned a few posts back. I'm fairly confident the camera is responsible for the largest error here, especially since I can see a lag in the rangefinder patch moving when I change focus direction from near to far. When I turn the lens the rangefinder patch moves with a slight delay. No lag the other way around when moving focus from far to near. 

[lct]

Too bad there is no Voigtlander digital camera, pretty sure some people would like it... My experience with cameras made by Cosina was limited to the Epson R-D1 that i liked much but i would not say that RF accuracy was its forte. 

[lct]

36 minutes ago, hmzimelka said:

[...] I'm fairly confident the camera is responsible for the largest error here [...]

My M11 is spot on but why not returning yours if you think it's faulty? 

[hmzimelka]

1 hour ago, lct said:

My M11 is spot on but why not returning yours if you think it's faulty? 

I will be returning it, it's just a HUGE hassle. I'm likely to sell it then if I don't get a poor offer. 

I need to get it to South Africa first. This is a problem as we are not allowed to send shipments out of Namibia without declaring a value with a Customs Invoice. The receiver needs to pay VAT Tax on that, which for a M11 is substantial. If its a low ball value then the carrier won't insure it for more than the declared value. This is the same issue getting the camera back from South Africa to me, I need to pay import VAT on that. Saying the camera is leaving for repair doesn't change anything, and I need to claim back the VAT then from the receiver of revenue, which is practically impossible. I'm still owed close to the equivalent of $2000 USD from them for the return of the faulty M10M and Summicron 35 ASPH from December last year. They don't know how to do it. 

Then from South Africa, it needs to be shipped off to Germany for who knows how long.

I need to essentially fly or drive to Cape Town South Africa to drop off the camera. Not exactly something I can do over a weekend, and driving 4000 km there and back is a considerable expense, and flights are even more expensive. 

Edited September 26, 2022 by hmzimelka

[lct]

11 minutes ago, hmzimelka said:

I will be returning it, it's just a HUGE hassle. I'm likely to sell it then if I don't get a poor offer. 

I need to get it to South Africa first. This is a problem as we are not allowed to send shipments out of Namibia without declaring a value with a Customs Invoice. The receiver needs to pay VAT Tax on that, which for a M11 is substantial. If its a low ball value then the carrier won't insure it for more than the declared value. This is the same issue getting the camera back from South Africa to me, I need to pay import VAT on that. Saying the camera is leaving for repair doesn't change anything, and I need to claim back the VAT then from the receiver of revenue, which is practically impossible. I'm still owed close to the equivalent of $2000 USD from them for the return of the faulty M10M and Summicron 35 ASPH from December last year. They don't know how to do it. 

Then from South Africa, it needs to be shipped off to Germany for who knows how long.

I need to essentially fly or drive to Cape Town South Africa to drop off the camera. Not exactly something I can do over a weekend, and driving 4000 km there and back is a considerable expense, and flights are even more expensive. 

So you bought your body in South Africa if i understand well. It is then to the South African dealer to replace or refund the camera i guess or am i mistaking something? I know nothing about the law in force there though.

[hmzimelka]

13 minutes ago, lct said:

So you bought your body in South Africa if i understand well. It is then to the South African dealer to replace or refund the camera i guess or am i mistaking something? I know nothing about the law in force there though.

Yes, exactly. We don't have camera stores here unless one wants to buy an old Nikon D3100 for way to much money.

I highly doubt Leica would replace the camera. They barely even took back the M10M with its fairly prominent sensor bifurcation line. Who knows. I'd like to be pleasantly surprised, but I'm not optimistic.

Edited September 26, 2022 by hmzimelka

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[lct]

Leica dealers tend to seek shelter behind the decisions of Wetzlar in my experience (Europe) but they have not the right to do so. At least in countries where the contract of purchase is concluded with the dealer. In South Africa i don't know though.