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Are M lenses really interchangable?

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After spending most of the summer attempting to get my M8 rangefinders properly calibrated...unsuccessfully ...I am questioning if its really possible. The answer I keep getting is that its only possible if you send all your equipment (bodies and lenses) to Solms...and even then that that will favor a specific focal length and everything else will be a compromise. There must be something I do not understand...at least I hope thats the case... My assumptions....1. M8 s are calibrated at the factory to a very tight tolerance and that bodies should be interchangable 2. lenses at least when new should match the factory settings.. that is a brand new body and lens should in most cases focus perfectly upon leaving the factory..3. when calibrating a system ..the first step should always be to insure that the M8 body is within tolerances ..this then becomes the standard...4. lenses should be calibrated to a standard not to a specific body. Thus the issue of interchangable lenses...if both the camera and the lenses are adjusted ..then new lens may not focus on the existing body and worse ..when adding a new body the existing lenses will need adjustment. I could really use some help as I am facing sending back 2 bodies and 10 lenses .

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Roger - it's possible to get the M8 to focus properly providing you send the unit back to Leica where they have proper tool to do it. All my lenses so far focus correctly on my M8. I hear a Leica owner would carry an extra wrench to tweak his 90mm APO in case the focusing failed. tha's a definite no-no in my book. I had problem with a 50mm f1.4 pre-ash sold it got another same unit and it works fine.

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For the body, there are three calibrations:

 

1. The lens bayonet flange must be exactly parallel to the sensor and the correct "standard" distance from it, notionally 27.8mm. When I dismantled one of my M8s, I found no shims under the bayonet mount, instead the sensor is bonded to an aluminium plate and mounted to the same die-casting as the bayonet mount at three points with shims under each which set the alignment to within 0.005mm by using shims of 0.01mm. The use of three mounting points allows the sensor to be adjusted so that it is exactly parallel to the bayonet mount. Keep in mind that the wavelength of light is around 700 nm (700 E-9m), or 0.0007mm so that the tolerance is around 7 times the wavelength of light.

 

It gets more complex when you think about changes of temperature because they will cause the lens flange-sensor distance to change, not by much, but if you are setting up to 0.01mm - less than 1/10 of the thickness of a piece of paper - these changes will be significant.

 

I do not know the coefficent of linear expansion of the alloy used for the camera casting but if it was aluminium, it's 23 E-6/K; a change of 20 degrees C will change the lens flange/sensor distance by 0.0128mm, greater than the tolerance to which the distance is set to start with. My guess is they set it up at a temperature around 20 degrees C to balance the expansion over the expected operating temperature range. Temperature stability will have been one of the selection criteria in choosing the alloy for the M8's body.

 

2. The are geometric adjustments to the rangefinder so that the rangefinder patch aligns exactly with the main viewfinder image, specifically vertical alignment and magnification. The bane of an Epson R-D1 owner's life is that the rangefinder patch vertical alignment is frequently out. If the alignment is out, you do not see the "snap" at the correct focus point.

 

3. The rangefinder is entirely separate from the rest of the camera and uses the same bayonet mount as its reference point. There's a defined relationship between the front-back position of the focussing cam follower roller and the distance at which the rangefinder will be coincident with the main viewfinder image. Two adjustments to the rangefinder (the roller eccentric and the effective lever arm length) set the "gain" and "offset" of the system familiar to electronic engineers.

 

When it comes to lenses, turning the focussing ring changes the position of the lens barrel relative to the bayonet mount and in some cases (such as the 50/1.4 ASPH) adjusts the relative geometry of the lens elements). This changes the subject distance at which the image projected by the lens onto the sensor is in focus.

 

Focussing the lens also rotates the focussing cam which presses against the roller and sets the rangefinder position. The issue of lens alignment is to link the two so that when the lens is focussed at a particular distance, the rangefinder is set to the same distance. This is done in two ways. If the two are close, the cam is profiled to provide the correct match and adjusting the lens consists of rotating the cam relative to the lens mount to achieve the correct alignment. If the two are far apart (as, for example, in a 21/2.8 ASPH where the front-back movement of the lens barrel is rather less than the movement of the focussing roller), the lens will use a double helicoid so that as the focussing ring is turned, the lens barrel moves at one rate and the focussing cam at another. The relative rates are set according to the machined pitch of the helicoids and adjustment can be made by rotating one helicoid relative to the other. The whole thing can be fine-tuned in addition by profiling the focussing cam.

 

It's clear then that interchangebility can only ever be achieved by calibrating bodies to one standard and calibrating lenses to the same standard but independently. Fiddling with one body and one lens may achieve a workable result but you then lose the ability to exchange lenses.

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Roger--

You are right; any Leica M lens should work fine on any Leica M body.

 

But a couple things in your post caught my eye--

"... attempting to get my M8 rangefinders properly calibrated...unsuccessfully"; and

"The answer I keep getting is that its only possible if you send all your equipment (bodies and lenses) to Solms..."

 

Who is attempting to calibrate your rangefinders? And who is telling you that only Solms can do the job, and only with all your equipment on hand? In my mind, whoever says that doesn't really understand the matter that deeply.

 

Mark Norton's description of the issues involved is quite specific; see also Testreports, where Mr Puts states that in the M8, "... the tolerance level of the whole rangefinder adjustment chain has been narrowed accordingly. The tolerance level in film based cameras is a few hundreds of a millimetre, in the M8 that level has been reduced to a few thousands of a millimetre. ... This makes the M8 the most accurately machined and assembled M camera in history."

 

Charles's comment that it's not a good idea for a person who doesn't know his way around Leica rangefinder adjustment to attempt it is directly on target. I've known people who thought they knew what they were doing but in fact left the customer with a mess he would need to send elsewhere, logically to Leica, to undo the damage.

 

M lenses are interchangable on all M cameras. Nonetheless there have apparently been a few cases where some lenses have got out that need some adjustment; and there seem also to have been a few M8s escaping Solms with misadjusted rangefinders.

 

If you've had someone other than Leica adjusting your cameras and have not had anyone adjust any of your lenses, then send the cameras to Leica for rangefinder adjustment. If someone has messed with your lenses as well, then they need to go along with the cameras.

 

--HC

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Sorry I tried to be clear. First ....the cameras were left at Leica Service in Solms at the beginning of the Leica trip Guy has written about. One body seemed way off and the other appeared pretty close. The intention was to get a quick adjustment the day we were there by Leica service. They adjusted one camera and it was still off at infinity..Guy checked it. They sent both cameras back to the factory for QC ...this is what I was told they do with the tough cases(probably talking about me not the cameras). The person I am communicating with is Mr Kaufmann..who I believe is the head of the service organization in Solms. He just had my cameras and they went thru service twice..were sent back to the factory in Solms. ...I understand that they replaced the entire rangefinder on one camera. In the process they ignored all my instructions and information..which resulted in shipping my camera to florida where it got lost in the mail for about a week. Mr Kaufmann wrote that he hoped my cameras were adjusted but that I would probably have to send my lenses in for calibration ..and that I should send the bodies in as well. I believe that they will adjust both the camera and a lens if necessary ....but I am guessing . Why would Leica speculate that I will need to send my lenses in? Thanks for all the input...I am just trying to get my system operational and get back on the road shooting.

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..shims under each which set the alignment to within 0.005mm by using shims of 0.01mm...

Mark,

 

Are you certain that this is correct? (Respectfully) it appears odd that Leica could adjust tolerances to 5-micron precision using shims with 10 microns thickness.

 

Pete.

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Pete, yes, the shims always add distance between the lens bayonet and the sensor, I'm assuming the tolerance is plus or minus.

 

For example, if the target distance is 177, you'd add in multiples of 10 while the actual is < 172. You'd end up with the actual being 177 +/- 5.

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Roger--

Thanks for the elaboration; I had made some wrong assumptions.

 

They sent both cameras back to the factory for QC ...this is what I was told they do with the tough cases(probably talking about me not the cameras).

LOL

In the process they ignored all my instructions and information..which resulted in shipping my camera to florida where it got lost in the mail for about a week.

This is a second, different problem. I've occasionally experienced the same thing. They have a procedure; they think they understand the problem; they follow their procedure--and all the time, the specific instructions were under their noses and not followed. It's frustrating and annoying, but I've found the same kind of thing with other manufacturers as well.

Mr Kaufmann wrote that he hoped my cameras were adjusted but that I would probably have to send my lenses in for calibration ..and that I should send the bodies in as well.

Here I try to become a mind-reader. I have no idea why Kaufmann should say that. Maybe it has to do with things he knows that we don't. There has been speculation on this forum that M8 rangefinder calibration needs a different set-up than did previous M's. Perhaps something you said left him the feeling that you had had your lenses adjusted to the camera or your camera to the lenses, in either of which cases the lenses might now need to be readjusted. Perhaps he saw that you have a particular lens some samples of which have been known to give trouble. Or perhaps your humorous reference above may be right--they may indeed consider you a "tough case," meaning that you may be pickier than most customers, not necessarily a bad thing IMHO.

 

My suggestion is that you go shoot with your equipment. If it works to your satisfaction--as it should--the problem is solved. I don't know what to recommend if it doesn't. Either send it back for service or get rid of it in frustration, though I've always found myself the loser when I go with frustration.

 

Last night I checked my lenses on my M8. An old Summilux 50 seemed to backfocus by 50 mm on the first test, but only by 10 mm on the second. Aside from that, they all focused fine. I definitely need new eyeglasses, but I still say the lenses are interchangeable on all M cameras.

 

I used to work for Leica and have a great deal of respect for their products and their people. But sometimes I get frustrated with them, too.

 

I don't know what the problems are in this case, but I do know that Leica will take care of them if given the chance.

 

BTW--Since you're apparently in the US, I'd suggest at least talking with the folks at Allendale. They can't do everything Solms can, but they can do most rangefinder and lens adjustments. They might could explain why Kaufmann suggested you send in all the equipment at once, and they could certainly give you some guidance on what's causing the problem in general.

 

I'm really sorry for the difficulties you're obviously having, and for the bad taste it must leave in your mouth.

 

I wish you the best of luck in the matter, and I hope you keep us posted on its outcome.

 

--HC

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Thanks for the hopeful thoughts and advice to all. Operator error is always a possibility. I would be very interested to better undestand how leica tests for focus accuracy on an M8 and a M lens.

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Forgive this question if it is elementary, but I am in the M8 contemplation stage, not the expertise stage. I understand that in an ideal world, everything would be calibrated, and we might have seven different calibrated bodies for seven calibrated lenses. My question, however, is this: can I buy an M8 with the expectation of attaching my 35 mm, 50 mm and 90 mm lenses and having them focus properly without having the body calibrated (i.e., out of the box)? Prompt advice would be appreciated , since this would be a significant acquisition for me and I don't want it to be of limited or no use out of the box. Thanks.

John W

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John--

There's nothing elementary in the question. My answer is: Buy the M8; it'll work with all your lenses with no problems.

 

My M8 worked for me out of the box with all my lenses, which range from a 50/1.4 that I bought new with my M5 to a Tri-Elmar 28-35-50 which I bought just before Leica started coding lenses, and which I have just had coded.

 

The few exceptions to the "It works with all lenses out of the box" rule seem to fall into two categories:

 

1) There seem to have been a few M8s shipped with improperly adjusted rangefinders. This was primarily with the earliest cameras shipped, while the M8 was still hard to get.

 

2) Some of the most recent lenses, particularly but not only the 35/1.4 ASPH seem to have escaped the factory slightly out of tolerance. One poster here, Tim Ashley, had an extreme difficulty getting Leica to recognize the problem he was having; they seem to have thought he had simply recognized some design features of his Summiluxes. When he switched to the 35/2 ASPH and still had the same problem, he was able to get Solms to listen and understand. They found that the lens had a slight backfocus problem (i.e. was out of spec) which combined with the inherent focus shift of the design to make it unusable for critical work wide open.

 

It's always possible that you'll get a camera that doesn't work with your lenses, but it's quite unlikely. Even during the time that Tim's odyssey with the misfocusing lenses was unfolding, there were people buying the same lenses and finding that they worked perfectly with their M8's. (And there were also several cases of people discovering the same problems as Tim's in new lenses they had just bought.)

 

The best news is that if there's a problem with a body/lens combination, Leica has become aware of what to look for and how to solve it.

 

I say you're unlikely to have problems, and the M8 is a very satisfying camera that you should not deny yourself.

 

--HC

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I would be very interested to better undestand how leica tests for focus accuracy on an M8 and a M lens.

So would I. There was a poster several months ago who claimed that M8's are checked by viewing images on the focusing screen. I doubt that, but I'm willing to learn. When I asked him where he got that information, I got no response.

 

In pre-M8 days, rangefinders were tested by means of a very sophisticated jig. (I've seen the setup but never seen it used.) There's a device that slides into the lens opening and sets the cam follower to a particular point. (This is on a solidly floor-mounted rig to which the camera must also be firmly mounted.) Once that's set up, the technician looks through the rangefinder at a target about ten feet away as I recall that replicates settings for all three of the rangefinder's settings at once. If any or all of the guide images don't line up through the rangefinder, the setting can be adjusted by the technician. It's a very sophisticated design that has worked since the days of the M3, but it does rely partially on the technician's eyesight.

 

I assume that the M8 uses the same equipment for calibration, but I'm not sure since it has a different finder magnification. There may also be more trouble with the M8 due to the different frame sets in the viewfinder--possibly more flare, for example.

 

I've asked an acquaintance at Leica whether the M8 is adjusted at the factory the same way as previous M's, but haven't got an answer.

 

The other question in my mind is this: On the forum we hear of a fair number of instances of out-of-adjustment rangefinders; but is the number really larger than it was with previous M cameras? When they were introduced, communication was strictly word-of-mouth, so we would not likely have heard if a number of cameras were shipping with improperly adjusted rangefinders. On the other hand, in the ten years I worked for Leica, I don't remember hearing of a single M camera reaching the customer with a rangefinder that needed adjustment. Still, we weren't shipping as many M's at that time as is the case with the M8.

 

--HC

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Thanks for the reassurance. My M6 had a rangefinder problem almost out of the box, so that is not so out of the ordinary. Now..everyone call my wife.....

John W

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Roger - it's possible to get the M8 to focus properly providing you send the unit back to Leica where they have proper tool to do it. All my lenses so far focus correctly on my M8. I hear a Leica owner would carry an extra wrench to tweak his 90mm APO in case the focusing failed. tha's a definite no-no in my book. I had problem with a 50mm f1.4 pre-ash sold it got another same unit and it works fine.

 

It is not harmful to carry an allen wrench for the cam follower. That is a harmless user-adjustement, which may be needed from time to time (but not to adapt to one particular lens!)

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When I dropped off my 75mm Summicron at Leica UK on Monday I asked about rangefinder adjustment. I was told the following...

 

Leica UK cannot adjust the M8 rangefinder, all cameras have to be sent back to Solms.

 

The rangefinder is different from previous models and requires something like 6 points to be adjusted - by this I assume he meant that the rangefinder was adjusted for 6 different distances.

 

He acknowledged that sending the camera to Solms is inconvenient, but that is the procedure.

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Leica UK cannot adjust the M8 rangefinder, all cameras have to be sent back to Solms.

 

The rangefinder is different from previous models and requires something like 6 points to be adjusted - by this I assume he meant that the rangefinder was adjusted for 6 different distances.

 

I don't know about the 6 points but Leica UK told me the same thing (having to send M8s back to Germany) earlier in the year. I was told that they do not have a jig that can accommodate the different size of the M8 compared to other M bodies. They treated the M8 as if it was contaminated by Plutonium and refused to touch it or even look through the viewfinder and have a go at focussing it. All I got was "yes, I'm sure you are right Sir" and "we have to send it back to Solms". To be fair, the body (and various lenses) came back quickly (in a couple of weeks in various states of improvement) but the whole service procedure seems designed for maximum customer frustration.

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John--

There's nothing elementary in the question. My answer is: Buy the M8; it'll work with all your lenses with no problems.

 

My M8 worked for me out of the box with all my lenses, which range from a 50/1.4 that I bought new with my M5 to a Tri-Elmar 28-35-50 which I bought just before Leica started coding lenses, and which I have just had coded.

 

The few exceptions to the "It works with all lenses out of the box" rule seem to fall into two categories:

 

1) There seem to have been a few M8s shipped with improperly adjusted rangefinders. This was primarily with the earliest cameras shipped, while the M8 was still hard to get.

 

2) Some of the most recent lenses, particularly but not only the 35/1.4 ASPH seem to have escaped the factory slightly out of tolerance. One poster here, Tim Ashley, had an extreme difficulty getting Leica to recognize the problem he was having; they seem to have thought he had simply recognized some design features of his Summiluxes. When he switched to the 35/2 ASPH and still had the same problem, he was able to get Solms to listen and understand. They found that the lens had a slight backfocus problem (i.e. was out of spec) which combined with the inherent focus shift of the design to make it unusable for critical work wide open.

 

It's always possible that you'll get a camera that doesn't work with your lenses, but it's quite unlikely. Even during the time that Tim's odyssey with the misfocusing lenses was unfolding, there were people buying the same lenses and finding that they worked perfectly with their M8's. (And there were also several cases of people discovering the same problems as Tim's in new lenses they had just bought.)

 

The best news is that if there's a problem with a body/lens combination, Leica has become aware of what to look for and how to solve it.

 

I say you're unlikely to have problems, and the M8 is a very satisfying camera that you should not deny yourself.

 

--HC

 

Your statement I bolded and underlined above are pure hog wash. I have 2 M8 bodies and 6 Leica lneses, 5 of which are brand new. The 50 and 75 Crons, new lenses, do not focus correctly on either of my 2 bodies. The older one, a 90 Tele-Elmarit, which just came back from NJ for coding does not focus correctly either. The 75 back focuses and get worse as the distance to the subject increases. The 50 & 90 front focus. This is on both M8 bodies.

Now I am faced with sending at least one body and 3 lenses off for god knows how long to be calibrated. And then hoping they work on my other body along with my other lenses working on the body that was calibrated.

It's not much to ask that a $5000 camera and $2000-$3000 lenses BE RIGHT when they leave the factory.

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So would I. There was a poster several months ago who claimed that M8's are checked by viewing images on the focusing screen. I doubt that, but I'm willing to learn. When I asked him where he got that information, I got no response.

 

In pre-M8 days, rangefinders were tested by means of a very sophisticated jig. (I've seen the setup but never seen it used.) There's a device that slides into the lens opening and sets the cam follower to a particular point. (This is on a solidly floor-mounted rig to which the camera must also be firmly mounted.) Once that's set up, the technician looks through the rangefinder at a target about ten feet away as I recall that replicates settings for all three of the rangefinder's settings at once. If any or all of the guide images don't line up through the rangefinder, the setting can be adjusted by the technician. It's a very sophisticated design that has worked since the days of the M3, but it does rely partially on the technician's eyesight.

 

I assume that the M8 uses the same equipment for calibration, but I'm not sure since it has a different finder magnification. There may also be more trouble with the M8 due to the different frame sets in the viewfinder--possibly more flare, for example.

 

I've asked an acquaintance at Leica whether the M8 is adjusted at the factory the same way as previous M's, but haven't got an answer.

 

The other question in my mind is this: On the forum we hear of a fair number of instances of out-of-adjustment rangefinders; but is the number really larger than it was with previous M cameras? When they were introduced, communication was strictly word-of-mouth, so we would not likely have heard if a number of cameras were shipping with improperly adjusted rangefinders. On the other hand, in the ten years I worked for Leica, I don't remember hearing of a single M camera reaching the customer with a rangefinder that needed adjustment. Still, we weren't shipping as many M's at that time as is the case with the M8.

 

--HC

 

They also used a ground glass fixture that mounted on the back of the film cameras to check that a lens mounted on the bayonet mount actually focused correctly at those distances the rangefinder was adjusted to. If the image projected on the ground glass was not sharp/in focus then they shimed the mount.

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Surely, if it's such a problem, you may get lenses matched to one M8 body, but not the other... You would need to send both bodies and all your lenses away so that, not only are the lenses matched to the cameras, but both bodies are matched to each other too.

 

Otherwise, some lenses will be matched to body 1, and some to body 2

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Ed - it is all a matter of individual experience...I personally have used a rather large number of lenses on two M8 bodies - and the score is : Focussed correctly: 18 misfocussed: 0 -and I habitually used large apertures, and I do believe I recognize an out of focus photograph. So maybe the word hogwash is a bit strong. It might be better to say - one can get unlucky - but so can one buying a 10.000+ Euro Canon or Nikon or Hasselblad or whatever combination. Read the relevant forums..... The only things showing relatively few focus issues are small-sensor P&S cameras - but there one has DOF from the tip of ones nose to infinity.

Not that I would not be just as annoyed as you are.....

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