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Jun 08, 2012 Leica M rangefinder calibration service June 8, 2012 by Ming Thein 6 Comments I’ve had a number of enquiries about focus precision, rangefinder calibration and adjustment etc. In the last couple of weeks – I suppose it’s because of the need for precision highlighted by the Monochrom’s resolution and 50 APO’s resolving power.
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After some time of writing these pages, I am pleased, to provide the very first documentation, that should help people, who are less adventurous and do seek for information on technical matters beyond the manufacturers manuals. Before we start, one word of caution, you must read and understand as my legal representative urged, to have provided:
Disclaimer: The documentation, provided by me does only report the steps and procedures, I undertake at my risk on my property. When you work on your equipment by yourself, you do this at your own risk. I can not be held liable for possible damage, you might cause, by working on your equipment. If you have the slightest uncertainty about the described procedures or working on your equipment by yourself, stop reading here and move along to meet your Leica dealer of choice, who will have your camera shipped for service to Leica, which will result in the best possible adjustment for your camera.
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So as we cleared the formal things, let’s move directly to the interesting part. This documentation is about making basic adjustments on your Leica M6 rangefinder in 5 easy steps with the minimal equipment and costs involved.
Having just acquired a used Leica M6 with 50mm Summilux lens, I found after viewing the first prints, that focus was off ever so slightly. Further looking into this issue showed a slight misalignment of the rangefinder focus patch according to the infinity stop and lens markings.
Symptoms of a misaligned rangefinder:
There are 2 possible directions of misalignments - horizontal and vertical. This documentation deals with the horizontal alignment only. I might get dirty and add a few details regarding the vertical alignment too as soon, as my M6 shows first signs of being off vertically.
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I do these things for my own pleasure and curiosity in technical and mechanical applications. If you, like me, took apart every piece of equipment, you got for christmas since you were a child AND were able, to assemble it back to working order, the few exceptions now and then included, this documentation might be for you. To prevent your Leica M6 becoming one of those exceptions, you need the right tools for the job.
items, you need:
1 x Leica M6 classic
1 x Leica M lens
1 x tripod
1 x tape measure scale
1 x 5 meter
1 x string
1 x weight for string
2 x light stand
4 x clamp
2 x sheet of paper
1 x pen
1 x moon
1 x screw driver
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Q: Why you should stop reading now and move along with the other guys, jumping ship after the disclaimer?
A: Trying to plumb your bathroom armatures by yourself, you set the house under water, ruined the wooden floor,
the house electricity and your postmark collection, worth more than your Leica gear and still do not admit the fault.
A: As you could not find an exactly fitting screw driver for the rangefinder adjustment screw of your camera,
you tried to use a kitchen knife.
Q: Why you should keep reading?
A: As you could not find an exactly fitting screw driver for the rangefinder adjustment screw of your camera,
you used kitchen knife, which you have grinded in perfect fitting shape and measurement with an
angle grinder free hand. That’s the spirit - read on, for you, there is nothing to fear here.
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1. Step - the right time, the right place
Ideally, you should do this during a clear night with a nice and shiny moon in visible sight.
You don’t have a moon in your part of the world? Don’t worry, your case is not lost as any other clearly visible, contrasty subject, at least a few kilometers away will do. I found the beautifully lighted neon skyscrapers of Shanghais skyline a perfect target for focussing at infinity.
You need some space for setting up a focus range with at least two different distances in the short range.
Which distance depends on the focus distance marks, displayed clearly on your lens. You will ideally need 1 meter and something in the 3 - 5 meter range. If you life in a 2 x 2 meter shed, as you blew all your money for mouthwatering Leica lenses - step outside! There is plenty of space.
For making the adjustments, you need a table with good light - a wooden box with a candle in the field does work too.
2. Step - setting up the scene
Prepare the two light stands or anything portable, that holds a focus target without moving - no, your drunk friend, holding a cornflakes box doesn’t do well - tell him to beat it now.
Marking the two sheets of paper with one vertical straight line and a horizontal sinus graph works well. Clamp your handmade new focus targets on your light stands in the same height - not too low (for you back aching old folks) and not too high - your wife/ girlfriend might laugh at you, falling from a ladder while trying to read the focus distance on your lens.
Prepare the tripod with your camera attached. A quick release system (Arca Swiss or whatever works for you) is highly recommended, as you will have to mount/ unmount your camera a lot without changing precise setting on your tripod during the next steps.
focus target Leica M6, quick release plate,
Markins M10 ball head
Set the tripod and focus targets the same hight. Take the string and weight and prepare a proper plumb bob, attached to the center of your tripod, exactly marking the position of the middle of your tripod on the floor. The following point is very important: adjust your camera, to have the film plane exactly in the center of your tripod, level the center post and ball head, so your measuring device sits exactly in the same perpendicular axis to the floor. You want to check back the distance from your cameras film plane to the focus targets with the help of another person.
precise tripod position camera facing 1 meter target
Take out the tape measure and line up your two focus targets and tripod. Line up your first target at the close focus distance, marked on your lens (I took 1 meter with the 50mm summilux) and your second target at the 2nd distance (I took 5 meter with the 50mm summilux). You should align your two targets in an angle towards your camera. This way, you just have to loosen the panorama setting knob on your ball head and turn the camera to either target without changing your precise settings.
note the panorama setting on the ball head, the whole setup
set for the 1 meter target at 3 clicks ccw
You’re done - now let’s the adjusting begin.
3. Step - checking rangefinder alignment
I start with checking the rangefinder at infinity focus, to see, in which direction and how far the focus is off. To do this, it is easiest, to place one half of the moon on one horizontal border of the rangefinder patch and watch the moons misalignment, when focussing the lens at it’s hard infinity stop.
The same checking procedure is done with your two focussing targets and camera on precisely aligned tripod.
The only difference to the infinity checking is, that you now use the lenses focus distance markings to set instead of the hard infinity stop. I find it easiest, to precisely focus on the target and judge how much off the focus marking on the lens barrel is.
checking focus distance after precisely closer look
focussing the 1 meter target
God thanks, we Germans still build lenses with precise markings opposed to the items, Nikon, Canon and other DSLR manufacturers make these days - the focus markings and overall lens built of my cheap 90 mm Tele Elmarit M for 500,- EUR is way superior to my Nikon 300 VR, costing more than 6 x the price.
1.4 x magnifier on the 0.72 Leica M helps focussing
4. Step - turning screws
Prepare the right screw driver. This is the most important part of all procedures. I give you a few things, you should consider, to NOT DAMAGE YOUR CAMERA.
The only screw, you will touch here is the one for horizontal rangefinder adjustment (obviously). Take your Leica M6 without lens attached. Looking directly into the lens mount from the front of the camera you can see the rangefinder roller, which is engaged by the lens during changing the focal distance in operation. This roller has one big screw, you can see, when looking under the roller from 6 o’clock.
the biggest screw you see is yours
You want a screw driver, that EXACTLY fits this screw head. When using a conventional screw driver be VERY careful, as you approach the screw with an angle to the screw axis, resulting in easily slipping and damaging the screw or worse.
When attempting, to turn the screw, be VERY CAREFUL, to not put any force on the roller arm, other than a momentum around the screw axis. Do NOT bent the roller arm. Do NOT put force on the roller arm, as this results in even worse rangefinder misalignment or damage.
The screw has a quite big resistance, which is needed, to hold its adjustment over time. Be prepared for this. Concentrate on not slipping out.
The adjustments, you make will be VERY, VERY slight of an angle of the screw for a rather big adjustment on the rangefinder patch. 1/2 º in turning the screw already has a substantial change of rangefinder alignment. Move slowly and step by step. Make one slight adjustment. Attach the lens. Check focus. Repeat until proper alignment is achieved.
5.Step - the last one and final thoughts
After having the infinity focus adjusted - check focus at your two different short range distances.
Now comes the big downside of this homemade adjustment: You adjust only the linear alignment, where on your camera body the infinity focus is placed. With this adjustment, you have no influence on the following factors:
To fix these issues, you only have one chance - send your camera and all lenses to a qualified service department. Only adjusting each individual lens and your Leica M camera will lead to the best adjustment. Sorry, to disturb you with the bad news.
Now here is the trade off (what I do).
Although, you cannot adjust each lens individually this way - you can adjust your camera, leading to the best compromise with your M system, leading to a better image quality, than with no adjustment:
Q: You shoot your 50 mm mainly in the street at night wide open at 2 meter - 5 meter ?
A: Screw the proper infinity focus - you want to set your rangefinder, to have best alignment in the 2-5 meter range.
Q: What to do, if your 50mm and your 90mm are off in completely different directions?
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A: Easy one - at which focus distances do you shoot each lens the most? Which of the lenses you shoot at which
aperture range the most? Set the rangefinder, to have the best compromise for good focus.
More weight have your most used, longer lenses, mostly used wide open. Lesser weight in this equation have your lesser used wide lenses, shot mostly stopped down, as you probably won’t see that much of a misfocus as obvious as with the longer, faster lenses, you use.
Q: I am not satisfied even with the most adventurous acquired compromise. What do I do?
A: Bad news for you - sent your camera and lenses in for a professional adjustment.
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This concludes my short documentation on the horizontal rangefinder adjustment on my Leica M6. I hope, I could help one or the other Leica M user and successfully scare away some, who would have made things worse after reading the internet and getting the monkey wrench workout on their fathers precious, resulting at least in a nice pair of red ears and an expensive Leica repair invoice.
Please do not contact me, after or before having messed with your camera - read the disclaimer on top and think about, why Leica does not advise, to do this at home. Please consider a proper adjustment in their service facility, which I highly recommend.
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