M9 - coincidence at infinity

[jaapv]

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The point at which the roller enganges the helicoid maybe? And if you read my post you will see the adjustments are NOT independent - the whole point .

 

I suggest you ask Leica - it is not my design....

[Julian Thompson]

I suggest you ask Leica - it is not my design....

 

No - clearly it isn't, and clearly you don't understand it either! The midpoint of focus is automatically set as the thread is a constant pitch on the lens. Bending the arm would move the roller, yes, but has nothing whatsoever to do with a routine rangefinder adjustment.

 

No disrespect but there is a tremendous amount of work detailled in this thread - enough so that one could successfully adjust one's own rangefinder (as has been successfully done by 4 people I know of following the thread plus myself and carsten originally)

 

Feel free to add to the knowledge base by backing up your claims with some graphs or other information but otherwise just leave it - it isn't helping at all and just makes you sound daft to the people who actually do understand how it works.

Edited April 24, 2010 by Julian Thompson

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[dutchman]

youre' totally right Julian;)

your method is evidence based

Let the others show their methods and facts

Keep up the good work

[jaapv]

No - clearly it isn't, and clearly you don't understand it either! The midpoint of focus is automatically set as the thread is a constant pitch on the lens. Bending the arm would move the roller, yes, but has nothing whatsoever to do with a routine rangefinder adjustment.

 

No disrespect but there is a tremendous amount of work detailled in this thread - enough so that one could successfully adjust one's own rangefinder (as has been successfully done by 4 people I know of following the thread plus myself and carsten originally)

 

Feel free to add to the knowledge base by backing up your claims with some graphs or other information but otherwise just leave it - it isn't helping at all and just makes you sound daft to the people who actually do understand how it works.

Sorry, mate, you obviously don't know what you're talking about. A little knowledge is a dangerous thing....I suggest you read the official Leica M service books. You'll find the special "bending tool" there as well. Or even look at image #22 in Gunther Osterloh's book, where you can just make out the specific waist for bending purposes. Alternatively you could talk to any qualified Leica service technician. I'm sure he will be able to enhance your understanding. In a small way you are right, the bending is the setting that is rarely off in cameras that leave the factory and is the least likely to go out of adjustment. It is bad engineering too, imo, by the way.

I'm happy for those that are satisfied by the results they had with this DIY, but I am concerned about unsuspecting readers following your example, completely throwing their rangefinder out of whack and voiding their guaranty in the process. Basically rangefinder adjustment is NOT an amateur job and best left to professionals.

Edited April 24, 2010 by jaapv

[menos I M6]

The Jaap has spoken ;-)

 

So guys, that this discussion doesn't go out into an ugly knife fight two small comments:

Jaap is correct in one point, there is a special service tool, fitting into the small hole in the roller arm for adjustment of the arm's angle.

 

And for clarification - no, the arm is not physically bent, nor is it a "bending tool" of any sort, but instead a tool, to fine adjust the arm's position with a better leverage and to have a secure fix on the arm, when putting any momentum on either adjustment screw (as the people, who have set the RF by themselves - myself included - have experienced, does any screw adjustment without counter working the screw momentum result in other settings getting "off")

 

Second comment:

Julian, thanks a lot for the great thread and the collected information here, making function and adjustment of the RF sufficiently transparent for the people, who actually care about doing some work by themselves.

 

RF adjustment really is a servicing like sensor cleaning, changing a tire or repairing a leak in the roof.

Of course will qualified personnel do the job better than you!

But do you call up the specialist, every time, you have a flat tire or a speck on the sensor of your digital camera?

 

It costs one bump of the camera to get the darn thing out of alignment. It can cost up to many months for Leica, to realign that error prone thing again - a regular user of the camera system, who is qualified with good hands, a brain and some technical common sense simply has to learn and understand the RF adjustment.

 

Oh and I don't participate in knife fights - no arguments for me ;-)

[Julian Thompson]

This is beyond funny Jaap, and just shows how you will push a position rather than saying 'ah I see, sorry guys I was wrong'

 

So it turns out that the service tool is used to lock into the hole in the arm and effect an adjustment of the arm length as described by me. What an excellent tool. You don't NEED it of course, but it would be lovely to have it.

 

So, in my case I spend many tens of hours deducing how it all works, gradually, even publishing my errors along the way and getting help wherever I can and then, safe in the knowledge that I understand it I made some posts backing everything up with evidence.

 

You, on the other hand see a PHOTOGRAPH YOU CAN JUST MAKE OUT and then attempt to advise with the following:

 

There are three points of adjustment in that arm

 

WRONG

 

That hole takes a bending tool, to bend the arm

 

WRONG - It's the adjustment tool to allow you to hold the arm easier.

 

and bend for intermediate.

 

WRONG - You tell me I'm misadvising - this is the funniest thing I've read for a while!

 

You'll find the special "bending tool" there as well.

 

WRONG - No bending here mate.

 

And my own, very special favourite Jaap is this:

 

 

In a small way you are right, the bending is the setting that is rarely off in cameras that leave the factory and is the least likely to go out of adjustment

 

So, there is no bending tool and yet you KNOW that this adjustment is rarely off, and is not likely to go out of adjustment. Just how on the Lord's earth can you know that, since this is an adjustment that you have made up in your own mind. Quite simply you have fabricated the whole bending thing because you've seen the adjustment tool that has now been correctly identified and you've decided to try and have the last word on it by making up the idea that bending your camera arm would affect your close focus. The only thing that trying to bend that arm would affect would be your warranty, mate, when it snaps straight off ! It's unbelievable Jaap.

 

So if you really are:

 

concerned about unsuspecting readers following your example, completely throwing their rangefinder out of whack and voiding their guaranty in the process.

 

Then you'll obviously want to set the record straight and admit straight out that you've been talking unsubstantiated nonsense and that nobody, ever, should want to try and bend their camera. That in fact you've misunderstood and you understand now that there are only 2 adjustments - length of arm and eccentric roller cam position, and that you confess to making up the third adjustment solely to make yourself look dead clever.

 

Adjusting the rangefinder is no more dangerous or difficult than adjusting a derailleur gear set on a bike - you either understand what the screws do or you don't - there is no middle ground. And the adjustment is self checking - it either works and is in focus on your photographs or it's not - Like the gears - they either change smoothly and have the right end points, and don't jump between gears or they don't. Saying that an unsuspecting owner could put 'everything' out of whack is only like messing up the screws on the gear set. You just tweak them back in once you understand it - no biggie. Or maybe you know of a secret bending tool that you use to do the gears on your bike as well eh?

 

Honestly I don't mean to sound harsh but the scale of the nonsense here Jaap is absolutely incredible and you need to deal with it.

Edited April 25, 2010 by Julian Thompson

[jaapv]

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Bluff and bluster wont change a thing, but if you have to spend tens of hours to work something out that has been widely known since 1954 and leave out one part...However, ill withdraw from this thread. I dislike Internet fights intensely so lets leave at thanking you for your dedication.

[Julian Thompson]

I dislike Internet fights intensely

 

It's not a fight - it's me responding to something I'm reading that you're stating with the tone of authority by telling you that you're wildly wrong.

 

I'm then proving you're wrong and you're then retreating because you realise you're wrong.

 

Not a fight - I think you're a great guy and make some brilliant posts but in this series of posts you are talking baloney and that's that. Nothing personal whatsoever.

 

But OK - case closed let's move on.

[menos I M6]

Do you guys have experience with shimming your lenses between mount and lens body, to adjust lens to RF arm between several lenses?

 

I am still looking for the right material to do the shimming, as I have certain lenses, which get to infinity very differently.

 

How much do you shim? Are we talking 0.05 or even 0.1 Millimeters here?

[jaapv]

Shimming is normally done internally on Leica lenses.

[giordano]

WRONG - It's the adjustment tool to allow you to hold the arm easier.

<snip>WRONG - No bending here mate.

<snip>

That in fact you've misunderstood and you understand now that there are only 2 adjustments - length of arm and eccentric roller cam position, and that you confess to making up the third adjustment solely to make yourself look dead clever.

 

According to the only factory manual I have (easily found on the internet), the thing is a bending tool and its purpose is to adjust the rangefinder by bending the arm. All that Jaap got wrong is precisely what this adjustment is for.

 

In order for all lenses to couple accurately with the rangefinder, the axis of the roller cam must be precisely parallel with the axis of the shaft at the other end of the arm. If it isn't, there are two possible sources of inaccuracy, though I don't know which is more important. One is that as the arm rotates, the angle the roller presents to the rangefinder cam on the lens will change; the other is that the coupling will be different depending on the vertical position at which each lens's rangefinder cam contacts the roller. If the roller is exactly parallel with the shaft at the other end, both those factors are irrelevant.

 

The official use of the bending tool is in conjunction with a special 3-position gauge that mimics a lens focused at 10m distance whose cam contacts the roller at top, centre and bottom of the roller's width. If the rangefinder image remains stationary as the gauge is moved between its three positions, this adjustment is correct. If it moves, the bending tool must be used. Clearly this is (a) unlikely to go out of adjustment in normal use and ( not something one can adjust without a special gauge, so it's outside the scope of DIY rangefinder adjustment.

 

I have no idea whether or not the bending tool is also useful when adjusting the arm length and roller cam.

 

My source is the official Repair Training Program manual for "Camera Set, Still Picture KS-15(4)", a US military version of the M2 with M4 rapid loading takeup spool. The arm on my M8 looks exactly the same as the one in the diagrams in this manual.

 

FWIW there are a total of five adjustment points in this part of the rangefinder, although only the two Julian has explored are likely to be needed in ordinary DIY work.

[giordano]

Do you guys have experience with shimming your lenses between mount and lens body, to adjust lens to RF arm between several lenses?

 

I am still looking for the right material to do the shimming, as I have certain lenses, which get to infinity very differently.

 

How much do you shim? Are we talking 0.05 or even 0.1 Millimeters here?

 

We're talking hundredths of a millimetre here. According to the "Barnack" depth of field calculator, depth of focus near infinity with a f/1.4 lens on the M9 and a 0.02mm circle of confusion is 0.057mm.

 

Also, is your problem with the lens itself or the rangefinder coupling?

 

E.g. is the lens sharp when focused at infinity but the rangefinder images don't coincide? If so, shimming the lens will make things worse, what's needed is adjustment of either the rangefinder itself or of the rangefinder cam on the lens.

 

Also, for any except a 50mm lens, shimming the lens mount will necessitate adjustment of the rangefinder cam on the lens.

[adli]

According to the only factory manual I have (easily found on the internet), the thing is a bending tool and its purpose is to adjust the rangefinder by bending the arm. All that Jaap got wrong is precisely what this adjustment is for.

 

.....

 

My source is the official Repair Training Program manual for "Camera Set, Still Picture KS-15(4)", a US military version of the M2 with M4 rapid loading takeup spool. The arm on my M8 looks exactly the same as the one in the diagrams in this manual.

 

FWIW there are a total of five adjustment points in this part of the rangefinder, although only the two Julian has explored are likely to be needed in ordinary DIY work.

 

Talking about this manual:

http://www.pentax-manuals.com/manuals/service/leica_m2_service.pdf

[scc]

FWIW, none of my lenses match exactly at infinity in the rangefinder patch, but are accurate for near focus, and I've not noticed any problem with my photos for distant subjects.

 

For completeness sake I'd like to send it away, but in reality, I won't, because the results I'm getting seem fine to me.

[Guest mc_k]

...And the adjustment is self checking - it either works and is in focus on your photographs or it's not - Like the gears - they either change smoothly and have the right end points, and don't jump between gears or they don't...

 

What I don't have is a reliable test at a middle distance...how are you doing this? I guess in theory you just need to check the two extremes. (But to be convinced...)

 

Another thing I don't have is a reference lens. I have a number of lenses, too, but they have a good deal of variation.

 

On the other hand, I am skeptical that just leaving everything up to Leica will lead to the best possible results.

[Guest mc_k]

Talking about this manual:

http://www.pentax-manuals.com/manuals/service/leica_m2_service.pdf

 

thanks for this

[adan]

Cartoon: Woman in robe typing madly at the computer as her spouse looks on from the bedroom door. Clock on wall reads 2:15 am. Woman says, "I CAN'T got to sleep yet. Someone is WRONG on the Internet!!"

 

Get a life, guys!

 

Referring back to title of thread "Coincidence at Infinity" - Surely that was the title of a StarTrek episode?

[jaapv]

:D Well said, Andy. Sometimes we need to step back and take a good look at ourselves.

[Julian Thompson]

Jaap. Please accept my apology. You are right and I was wrong. There is a bending tool - you are quite right.

 

This does not alter the procedure for DIY adjustment - you don't bend anything to adjust the mid focus - actually bending that arm would only be necessary if for some reason the roller was not perpendicular to the lens - ie a manufacturing defect - it's a perpendicular adjustment of the roller, not a focussing one in the sense that we've been discussing here.

 

So the instructions must be revised - you need to check to make sure the roller is exactly perpendicular to the lens mount before you begin. I have checked both my M's and the roller is exactly perpendicular.

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Look here: Leica M

[jaapv]

No apology needed at all, Julian.

The reason that bending the arm (the tool will bend in the horizontal plane, (which is evident if you look at the construction) will affect the focussing is that the slope on the helicoid is non-linear, so the point at which the roller touches the slope will affect the relationship between the various distances, depending on steepness gradient at that point. You can find the correct point by bending until the images don't shift. Be very, very careful with that adjustment! If you can get it right with your original approximation method leave it at that.

Btw, non-coincidence can also have another reason and can occur with a perfectly adjusted rangefinder as expounded in the manual:

 

If the lines do not reasonably coincide at infinity, loosen the two screws (fig. 4-22)

and shift the entire bright-line frame assembly. Recheck alternately between 1-meter

and infinity. Readjust as necessary, with the guide rivet and by moving the mask

assembly, until coincidence is obtained at both settings. Coincidence at 1-meter

should be precise.

Edited April 26, 2010 by jaapv