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glenerrolrd

Are M lenses really interchangable?

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HC, maybe, but right now, I feel I'm drowning in a kind of mis-alignment soup. Unlike Jono, I've never had the same problems with Nikon equipment.

 

I'm trying to get a handle on the amount of backfocus people are experiencing. Let's get specific. Are we talking millimeters or inches?

 

For example my CV 40mm f1.4 backfocuses 6mm when it is wide open. Would that amount of backfocus be a case for concern?

 

Without anyone quantifing just how much backfocus is involved, it's a little hard to make any judgements about anything.

 

Rex

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Roger--

I agree completely. If you'll notice, my repetitions have simply been in response to people who are themselves repeating arguments that have already been answered.

 

Still open is the question I raised above about early adopters / late adopters. Ed's answer was off the topic, answering with serial numbers, and you didn't respond at all. That makes it look as if you're not serious about the question you raised in the thread title.

 

You say you and Ed looked at four bodies. What about Carsten's eight (wasn't it) mentioned above?

 

As I said, I'm glad you opened the thread. But anecdotes aren't evidence. Quantify.

 

Your complaint that I'm repeating myself doesn't cite any repetitions and shows no ellipses. That's sloppy editing.

 

Nor, as I read it, does your latest post say anything about the results of your and Ed's test. You say you had a certain number of bodies and lenses and agreed about results within 5 mm, but you skipped reporting on your findings. You say you opened the thread with a purpose, and here you are apparently ignoring the purpose.

 

--HC

Howard I don t think we are on the same page on anything. I am trying to determine if other people are finding that there focus problems and how they are dealing with them. There were page afer page of instructions on how to adjust the M8 rangefinder . I know for a fact that more than a few people are having this problem. Now if you choose to feel that its only a rare and unusual circumstance..then you are entitled to your opinion as am I . I don t feel I need to say anything more on whether this is a real problem or not. Your questions all seem to be attempts to dismiss the issues I have attempted to raise. I was attempting to draw out others that are dealing with the same issues .....at this point you are succesfully undermining this objective. As I said in my last post ..if you don t have anything to add other than the problems an exception..please do something else with your time. As to answering your questions, supplying detailed information and whether you think my discussion is solid enough... I find your tone unacceptable.

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As I said in my last post ..if you don t have anything to add other than the problems an exception..please do something else with your time. As to answering your questions, supplying detailed information and whether you think my discussion is solid enough... I find your tone unacceptable.

 

The only people who can say if it's exceptional or not are Leica. They have the stats. A thread where several people say 'hey I've had the same problem' proves nothing other than the fact that they've had the same problem that you have. Obviously some cameras are going to ship with badly adjusted rangefinders, and some lenses are going to ship with poorly aligned focussing cams, but you can't judge the level of the problem in a self selecting thread like this

 

It's a bit like someone saying "I've got cancer, has anyone else?" and then some other people saying "I have too" and drawing the conclusion that everyone has cancer with just a few exceptions. To get the true figures you have to do a survey that is random and not self selecting.

 

Yes some people have a problem. Is that problem severe or not? We don't know.

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I'm trying to get a handle on the amount of backfocus people are experiencing. Let's get specific. Are we talking millimeters or inches?

 

For example my CV 40mm f1.4 backfocuses 6mm when it is wide open. Would that amount of backfocus be a case for concern?

 

Without anyone quantifing just how much backfocus is involved, it's a little hard to make any judgements about anything.

 

Rex

You are absolutely right. I have asked this questions a dozen times of both Leica and other leica repair services (DAG) . I never seem to get a complete answer ..its always ..they should focus perfectly. Unfortunately most of us have to rely on the quality of our eyes and our focusing skills with the M8. Here are a few findings facts from my tests this morning...at 4.5ft focusing on the Tom Hogan test chart from a 45 degree angle on a tripod using a cable release.....we found that we could focus within + or - 2mm..so thats our focus inaccuracy variable. On a 50 summilux at 1.4 if you were dead on everything from -2mm to +6mm looked sharp .it was sometimes hard to determine where the absolute best focus was.. That is I know that its between say 2mm back and 6mm back but it so close it might be between them. Since this is with a test chart using a tripod and have 2 people check everything... I am sure that you will have to work to achieve + or - 10mm at 4.5 ft . 6mm seems to be within a reasonable tolerance for a 40 1.4..just my opinion. However you may find when testing other lenses that if they all backfocus ..your 40 might benefit if the camera was adjusted ..if other lens are all satifactory then you may be fine. I would be interested in other opinions as I have no standard of acceptable tolerance. I should note that we were using 1.35 magnifiers with adjustable diopters and had a very bright light shinned on the test chart.

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Graham--

Maybe British and American usage differ.

 

How much was the backfocus?

 

Were the bodies consistent among themselves? Were the lenses consistent across bodies?

 

--HC

 

The back focus was reasonably constant across the 4 faulty bodies but varied with the lens used.

 

The back focus was sufficient to put the point on the chart that I had focused on outside of the DOF area. i.e. if it had been a real photograph then the intended point of focus would have been out of focus.

 

I tested with tripod, timer release and focus chart.

 

As I have posted at length in other threads, I do have a body at the moment that focuses acceptably but it is electronically faulty. With this body the plane of focus varies slightly lens to lens but is always well within the DOF area.

 

All tests with lenses fully open.

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I'm trying to get a handle on the amount of backfocus people are experiencing. Let's get specific. Are we talking millimeters or inches?

 

For example my CV 40mm f1.4 backfocuses 6mm when it is wide open. Would that amount of backfocus be a case for concern?

 

Without anyone quantifing just how much backfocus is involved, it's a little hard to make any judgements about anything.

 

Rex

 

As far as i am concerned, if the back (or front) focus puts the intended point of focus outside of the DOF area then the body is unusable as what you focus on will be out of focus.

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You say you and Ed looked at four bodies. What about Carsten's eight (wasn't it) mentioned above?

 

I have had only one body, but have tested many lenses. The eight I own or have access to right now are all within my personal satisfaction threshold, but I couldn't tell you what that is. I did have to tune the rangefinder in my camera myself, and send my 50 Lux Asph back to Solms twice to get to this point. I tuned it by referring to several lenses alternatingly while tuning, and two of the lenses were also tested on a known-good-body at Leica Camera Berlin, IIRC. All three rangefinder settings were tuned, ie. infinity focus, infinity/near balance, and vertical offset. I used a star in the night sky as my infinity, and a 1m and 5m point in my apartment. There is a thread about all this somewhere.

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You are absolutely right. I have asked this questions a dozen times or both Leica and other leica repair services (DAG) . I never seem to get a complete answer ..its always ..they should focus perfectly. Unfortunately most of us have to rely on the quality of our eyes and our focusing skills with the M8. Here are a few findings facts from my tests this morning...at 4.5ft focusing on the Tom Hogan test chart from a 45 degree angle on a tripod using a cable release.....we found that we could focus within + or - 2mm..so thats our focus inaccuracy variable. On a 50 summilux at 1.4 if you were dead on everything from -2mm to +6mm looked sharp .it was sometimes hard to determine where the absolute best focus was.. That is I know that its between say 2mm back and 6mm back but it so close it might be between them. Since this is with a test chart using a tripod and have 2 people check everything... I am sure that you will have to work to achieve + or - 10mm at 4.5 ft . 6mm seems to be within a reasonable tolerance for a 40 1.4..just my opinion. However you may find when testing other lenses that if they all backfocus ..your 40 might benefit if the camera was adjusted ..if other lens are all satifactory then you may be fine. I would be interested in other opinions as I have no standard of acceptable tolerance. I should note that we were using 1.35 magnifiers with adjustable diopters and had a very bright light shinned on the test chart.

 

Roger

So you are saying that you and your friend are capable of +- 2mm in focus repeatability at around 55". That's pretty darn good, think about it....that's +- 80 thouthenth of an inch. But what if the rangefinder measuring the distance to the subject is off by 1% in absolute distance? So I% of 55" is about 13mm. Whoops, your screwed already and we haven't even begun to talk about errors of the lens. Well I could go on and on, but the fact is getting everything within a 1/2'' is pretty good. Now since the acceptable depth of field of the Summilux is about a 1/2" by itself, you can see that your own focusing error can be enough to throw the whole thing out.

But it is much worse than just that. In real life, the camera is bobbing around about +- 1" will the subject is doing likewise. Meanwhile you are trying to focus at the same time. That's why experienced rangefinder users bob their own head to do the final focus "touch up" before shooting. It's a little like a cross between target shooting and a crap shoot. Unless you make a career of shootiing inclined rulers on a tripod, minor backfocus issues are more a subject for pixelbators than photographers.

That being said, if the camera or lens is off by centimeters, their may by a real problem. And I don't doubt that their are many cameras and lenses out there that have real problems. My point is that just because you can detect some backfocus in your camera/lens combination does not mean a trip back to Solm.

 

Rex

Arf..Arf!

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...we found that we could focus within + or - 2mm..so thats our focus inaccuracy variable...

 

Well that's certainly not something _I'd_ never be able to achieve, with a rangefinder, SLR or even an autofocus SLR <grin>

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As far as i am concerned, if the back (or front) focus puts the intended point of focus outside of the DOF area then the body is unusable as what you focus on will be out of focus.

 

London

 

Well with the 50mm f1.4 that would be +- 1/2" . That's just about at my limit of focus repeatability without the magnifier. Therefore, if you demand 100% focus accuracy, the tolerances of your camera/lens combination must be exactly 0.

 

Perfection is a little difficult to obtain in a factory setting

 

Rex

Arf

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Well with the 50mm f1.4 that would be +- 1/2" . That's just about at my limit of focus repeatability without the magnifier. Therefore, if you demand 100% focus accuracy, the tolerances of your camera/lens combination must be exactly 0.

 

I think this seems reasonable, but with 50mm 1.2 and 80mm f1.4 noticable blurring will occur when focus is off by one millimeter for an object at 2 meters.

 

Most users would be very happy if they could focus a 1.4 lens within a few millimeters. But I don't think that is what the complaints were about.

 

While no manual or AF system seems to be this accurate it appears that some photographers using slrs can routinely achieve this level of accuracy through observation on the viewing screen and simply moving a little and shooting when the subject is in focus. I have a good friend who readily achieves this level of accurate focusing with the Canon 85 1.2 and 135 f2 shot wide open. He also uses Leicas so I'll have to ask him if he can do the same with one of those.

 

If the M8 rangefinder and high speed lens is very accurately adjusted, you may be able to achieve this level of accuracy by moving in and out slightly and observing the overlap. But I'm not sure if this level of accuracy is reasonable to expect in any rangefinder system.

 

Here are some interesting tests on focusing accuracy.

 

diglloyd: Autofocus Accuracy

 

diglloyd: Autofocus Accuracy

 

That being said, a lot of the complaints are about rangefinders and lenses that were way off. There is this thread right now where the owner's Noctilux was off by about 80mm when focused at 1120mm and used at f2.8:

 

http://www.l-camera-forum.com/leica-forum/leica-m8-forum/29719-focus-problem-help-needed-pls.html

 

He says that all seems fine with the lens and camera past 6 meters.

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K... for what it's worth...

 

Out of the box, my M8 backfocussed a little bit, consistently, by about 4 inches at closest range, and you could tell with all lens beyond 35mm in length (so the 35, 50s and 75) wider than f2.8.

 

After a single minor infinity adjustment, all my lenses focus properly from wide open to f8. That would be the 15 CV, 21 CV, 24 Elmarit, 28 CV 1.9, 28 Elmarit ASPH, 35 Lux ASPH (sharp as razors) 50 Lux 1.4, Nocti (the one I had for a week).

 

Once adjusted, the (used) 75 Lux seemed out--it frontfocused by about 8 inches closed up wide open. Sent that to Kindermann Canada, where they told me the lens could not acheive infinity focus and needed repair. One repair later, it's great at f1.4, too.

 

So yes--your chances of getting an M8 to focus with multiple lenses very accurately are good. Yes I had to adjust the rangefinder a wee bit; yes I had to adjust my Canon 1ds2 and 1d2 as well

The 5d seems ok (but the 50 1.2L definitely has wide-open close focus shift).

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London

 

Well with the 50mm f1.4 that would be +- 1/2" . That's just about at my limit of focus repeatability without the magnifier. Therefore, if you demand 100% focus accuracy, the tolerances of your camera/lens combination must be exactly 0.

 

Perfection is a little difficult to obtain in a factory setting

 

Rex

Arf

 

I dont understand your reasoning? If what you say is right then what on earth is the point in my buying a 50 1.4 if you are saying it can never be focused reliably at f1.4 ???

 

I know it can be done because I can get repeated accurately focused shots at 1.4 with the body I have at the moment (electrically faulty)

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I know the problem with all 4 faulty bodies was the camera range finder adjustment because with all 4 it was usually possible to get correct focus by aligning the patches and then turning the lens focus ring a few degrees 'shorter' or clockwise from the behind the camera.

 

I am just not prepared to start tying to adjust a brand new camera myself.

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I dont understand your reasoning? If what you say is right then what on earth is the point in my buying a 50 1.4 if you are saying it can never be focused reliably at f1.4 ?

 

The point is that you probably don't spend all your time photographing wide open at the minimum focussing distance. It really is very, very, difficult to get consistent results under real world conditions at that distance. DOF really is very shallow at that distance and it only needs a small movement on the part of the photographer or subject to compromise the focussing. My _personal_ feeling is that anyone who expects to get 100% perfectly focussed shots in that situation is going to be disappointed.

 

At this point I should confess I haven't taken any photographs of rulers, nails or tape measures, I've only used the camera to take photographs and I haven't noticed any issues that I could attribute to a faulty body. Again, I'm not saying that some people haven't experienced issues with their cameras/lenses.

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The point is that you probably don't spend all your time photographing wide open at the minimum focussing distance. It really is very, very, difficult to get consistent results under real world conditions at that distance. DOF really is very shallow at that distance and it only needs a small movement on the part of the photographer or subject to compromise the focussing. My _personal_ feeling is that anyone who expects to get 100% perfectly focussed shots in that situation is going to be disappointed.

 

At this point I should confess I haven't taken any photographs of rulers, nails or tape measures, I've only used the camera to take photographs and I haven't noticed any issues that I could attribute to a faulty body. Again, I'm not saying that some people haven't experienced issues with their cameras/lenses.

 

OK I agree with you mostly here but 5 inches back focus and never being able to get a sharp shot of a stationary subject at 1.4 with a tripod is not acceptable to me.

 

Plus the fact that I can get in focus shots with the camera I have at present (electrical fault)

 

I am not looking for an argument with anyone here or even looking for answers (I know the answer) all I am saying is:-

 

1. Yes M lenses are interchangeable and I have a camera that works (focus wise) to prove it.

 

2. There are a lot of faulty M8s out there. I have had 5 out of 5 that are faulty and 4 of them had back focus issues.

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There is something which I haven't seen discussed here yet. Certain situations seem to provoke errors in certain directions. When I have sat down and carefully tested and re-tested, for statistical validation, my lenses, they are on. However, if I leave my 1.25x loupe off, I always focus my 90 Macro too far back, and never too close. I have similar consistent failure modes with some of my other lenses, like the 50 Lux Asph.

 

I would suspect that it is possible that the ruler test is such a case, and that it is possible to have a lens which one consistently focuses wrong in some direction, although it is actually not that far off, or not off at all. I am not pointing the finger at anyone here, just pointing out that the "rigorous" testing that some try to do may have its own problems independently of whether the lens in question has a problem or not.

 

I would say that the best testing one could do would be taking lots and lots of pictures of the kinds you want to do with that lens. If you can focus it correctly, then forget what the ruler test says. Under these circumstances, the situation might look a little better than otherwise.

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Carsten,

I would tend to agree.

My eyes are not in great shape, but corrected to 20-20 with glasses, and that tended to make things worse for me.

I found that for longer lenses, if I were to approach rangefinder coincedence clockwise or anti-clockwise, I would get different results systematicly.

This magicly went away after I re-tried my tests with two stacked magnifiers.

The worse part was that I had tweaked my infinity adjustment based on some initial tests which led me astray and tended to foul up the aparent performance of several other lenses.

After some *VERY* careful re-tweaking of that same adjustment, all seems to be well.

I don't think that the clockwise or anti-clockwise approach to the focus point had any significant hysterisis. Most of my issue was my technique and a bit of a rush to judgement.

The summary result is that longer lenses require focus with malice and forethought after you practice with your own eyes and learn their characteristics as well as those of the camera and lens.

Finially, I tended to get more consistent results using a diopter correction and tossing the specs.

-bob

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Finially, I tended to get more consistent results using a diopter correction and tossing the specs.

-bob

 

That is because the VF is set at a fixed distance, theoretically, of 2 meters (about 7 feet).

So when you look at something through the VF what you are really looking at is a type of projection. This can change slightly depending on how far or close the subject is.

 

I normally wear 1.5>1.75 reading glasses for everyday computer work and book reading. When using either of those 2 strength glasses for viewing through the VF of the M8 or M3 near subjects, 3-4 feet, are fairly sharp but if I try to focus on something that is 7-10+ feet away it is blurry. With the M3 I didn't find a need to go the screw in diopter route because of it's larger .93 magnifier I would just put my glasses on for close subjects and remove them for more distant subjects. But with the M8's .68 VF magnification I found neither glasses on or off worked well for either close or far subjects.

That is when I started looking for diopters.

Since the M VF is also set at a -.5 diopter I figured a +1.5 would be ok but that was not true. I then tried a +2 diopter, figuring that the -.5 of the VF and the +1.5 of my normal reading glasses would equal the +2. Well that was totally wrong, that made everything worse. It was then I did some reading and found that the VF is set at 2 meters. At 2 meters I see pretty good without any glasses. I then tried a +1 diopter and that is ware I am now and everything in the VF is clear.

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OK I agree with you mostly here but 5 inches back focus and never being able to get a sharp shot of a stationary subject at 1.4 with a tripod is not acceptable to me.

 

Plus the fact that I can get in focus shots with the camera I have at present (electrical fault)

 

I am not looking for an argument with anyone here or even looking for answers (I know the answer) all I am saying is:-

 

1. Yes M lenses are interchangeable and I have a camera that works (focus wise) to prove it.

 

2. There are a lot of faulty M8s out there. I have had 5 out of 5 that are faulty and 4 of them had back focus issues.

Graham I believe you are correct that you can have a fully interchangable lens system. If could share with us two things 1. How did you satsify yourself that your camera / lens was focusing properly? In otherwords what do you believe should be reasonable expectations for focus accuracy and how did you get comfortable . 2. Ultimately where any of your lenses requiring adjustment and did you have them matched to your specific bodies? Same as above ..how did you accomplish this.

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