How to precisely tune your rangefinder in 15 minutes or less

[Englander]

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After reading of John Milich's and others ordeals in accurately adjusting their rangefinder, I would like to offer to some help. My technique adds two elements to those that have been previously extensively discussed on this site: magnification and a focusing mount.

 

Since the adjustments are expected to increase the precision of a potentially very accurate system, you must understand that the resulting precision will be directly proportional to your care, patience, and the use of some aids that you might not normally have on hand--how much you consider the extra precision to be worth will be a determiner. You may have to team up with some friends to allay some of the cost.

 

You will require a lens, such as an older 50 Summicron, from which the lens cells can be removed. The 50 is ideal because the focusing mount itself is quite short and allows the use of the required 2mm allen wrench to adjust the eccentric roller cam. When removing the lens cell from the focusing mount, make certain not to lose or damage any of the shims; shims are a hallmark of precision German engineering.

 

You MUST use at least one focusing magnifier, such as the Leica 1.25, but preferably two or maybe three. The Leica versions can screw into each other; the MAP/HK 1.35 versions can screw into a Leica 1.25 but not vice versa. The more magnifiers you use, the more accurate your adjustments will be because you can more accurately evaluate the rangefinder patch.

 

You need to have a target that is truly at infinity; one-quarter of a mile or more, for example. A lamp post or telephone pole is ideal because it allows use of both coincident range finding and split image. The later will provide the fastest and most accurate results.

 

First, check to see IF the rangefinder is actually out of adjustment at infinity. Mount the camera on a tripod and focus it on a telephone or light pole at infinity and position the image so the poll runs through the finder patch. If your range finder is out--peering through one or more magnifiers-- there will be at least a slight offset of the poll when your lens is focused at infinity; for this test, the longer and faster, the better: --eg 50 or 75 1.4, 90/2 or 135. If there is no offset and you think your lenses are not focusing accurately at close distances, you will need to use additional techniques to what I will describe here; the best alternative requires a $100 macro focusing rail and and a resolution chart. In general, however, I have found that most Leica owners do not focus accurately at close distances and blame their cameras for operator errors, so any separate close focus adjustments are usually not needed and ill-advised. Really, before you blame the close focus adjustment, examine very carefully the split image at infinity using multiple magnifiers to be very, very certain that there is no image shift at all in the finder. Casual observation is not enough. I say this from experience. What appears sufficient without a magnifier or with cursory examination will not provide the desired results. You really have to look very closely.

 

If there is image shift in the split image of the finder, then continue:

 

When facing the camera, with no lens mounted, insert the 2 mm wrench into the center of the roller cam and turn to your left. Yes, this will definitely put the rangefinder out of position and that is what you want: a definite error. Now attach the focusing mount (with the lens cell removed), turn the mount to infinity position, reinsert the allen wrench and hold it in place while moving to the back of the camera. The camera should still be aimed at the pole, the lens mount should absolutely be turned all the way to its infinity position. From the back of the camera, while looking through the viewfinder, turn the the wrench to your left until the split image is exactly aligned. How exactly you align the image, will affect ALL other focusing positions. Be very, very exact. Use multiple magnifiers. Remove the wrench and turn the the lens mount focusing unit back and forth, returning to infinity position and confirm your correction. Mount your lens with the least depth of field and make certain it is producing the same alignment in the patch.

 

Make images to test the focusing at various distances. It should be absolutely accurate. If you have previously fiddled with the close-focus adjustment, all bets are off. The position of the close-focus arm as set by Leica is quite exact; it is usually the infinity roller position that throws off close focus.

 

I have attached photos to show what I mean by accurate---the near eye of a subject at 1 meter, a resolution chart at 3 meters and the inevitable 45º chart at 0.7 mtrs. While the latter may be slightly "off"; I think it rather illustrates the fallibility of that focusing chart's results with a titlted camera since the other tests are so convincing; but that is another argument.

 

Now, for what I consider to be the really scary part. When delivered new, my M8 focused perfectly at all distances. After two overseas assignments, I noticed that infinity was no longer coincident in the rangefinder. When I returned to the USA, I sent the camera to NJ for emergency warranty adjustment of the rangefinder; I was much too busy at the time to want to fiddle with adjustments. The camera was returned to me with better focusing than when I sent it, but it was not as accurate as it was when new. For that reason, I undertook the remediation I have described. But what really troubles me is whether the rangefinder is going to go out on a continuous basis without warning; will I constantly need to check it in order to have accurate focus. Only time will tell. I hope that things stay adjusted!

 

 

Joe

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[luigi bertolotti]

Compliments, a precious and well detailed work for people that has no fear to put their hands into M8 mechanism... and let's hope that the M8 RF proves reliable... it would be VERY ANNOYING, even for a person who loves hand tools, to have the RF to be adjusted evry year or a couple of...this is the thing that REALLY could put Leica Co. in serious trouble: none of us finds it strange that Leica cannot develop its own sensor... but their mechanical excellence is a VALUE they have to maintain carefully: my M4 has needed a RF adjustment axactly at its 40th birthday...

[jlm]

Joe:

are you assuming that if the lens is set to infinity on its scale it will produce an image that is sharp, regardless of what the rangefinder says?

 

not sure where I'm going to get a gutted lens, but sounds like a plan.

 

i assume the focuing rail part is still to come...

[innerimager]

Joe- Thanks for the excellent post. Are you anywhere near New York City? If so, I'd like to offer to come and pay you to adjust mine and teach me to. Hell, might even take a plane! not kidding! best....Peter

[marknorton]

Joe, very interesting. The lens I use for this purpose is the old-style 50/1.4 - the version that was around in 1990 before it was updated to include an integral lens hood. With this lens, the lens barrel unscrews from the focussing mount which I can then use as an infinity reference.

 

Lenses and bodies can only be inter-changeable if they are calibrated to independent references, not to each other. There's a defined relationship between the position of the rangefinder roller and the resulting distance at which the rangefinder image is coincident. This focussing mount - assuming it is itself correct - provides a reference for infinity but I would like Leica to provide a calibrated mount at, say, 0.7m, 1m, 2m, 5m, 10m, Infinity. That way, the body can be checked without relying on a lens for the calibration.

[Shootist]

What lenses can be unscrewed from the focusing mount. Damn I knew I should kept my old 50mm.

[Englander]

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@jlm, doesn't require a "gutted" lens. Almost any 50 Summicron, up to the integrated hood version, allowed the unscrewing of the lens cell. Many others had cells that could be unscrewed for use in visoflex and bellows. If you do not want to buy, just borrow an f/2. Unless the lens is damaged, the infinity position is reliable enough to make the assumption that no matter what the rangefinder says, the lens is at infinity and the rangefinder needs adjustment. Turn the lens to the infinity stop, do not try to "read" the scale.

@ sorry Peter, I am not near NYC. I suggest getting a 50 Summicron on "approval" from one of the used camera stores

@ Mark, as usual, you are precisely correct. Unfortunately, none of us has the "standard" available for our own use. I too wish such a mount were available but just using the Summicron as described resulted in a pragmatically precise adjustment.

 

Joe

[jlm]

just very carefully set my 75 apocron at infinity (using one 1.35 magnifier) by tweaking the roller, lens set up against the inf stop and shot a few images of a lamp pole at at least 1/4 mile. images look pretty sharp. then re-shot my 8' away test image of text by setting focus on a vertical in the text, then chimping. without changing the focus position on the barrell, i had to move the tripod back six inches to get perfect focus. (all shot at f2.8)

 

my 50 is a lux, don't know if it comes apart, so ahd to do the less optimal way of looking, removing lens and tweaking roller, replacing and re-viewing.

 

ok this is interesting. used an old 50 cron mount as per Joe, and found the distant lamp pole was not indicated as in focus by the RF, even though it show it is with the 75 apo! put on my 50 lux...same as the 50 cron mount, put the 75 back on, still showing focus.

 

so my 75 needs tweaking!!!

now i will reset inf using the 50, then test near focus again.

[carstenw]

John, my personal experience by looking out from where I work (9th floor, in Berlin that is pretty high and I can see for many miles), is that even with my 35 Cron Asph, I can actually detect a difference between focusing at around 1-2km (0.8-1.4m or so), and focusing several kilometres away. The rangefinder shows the difference clearly. In other words, 1/4 mile is not a reliable infinity. Try to get up higher, and find a spire in the distance, or even better, wait until night time, and use a star. That is what I did when I tuned all three aspects of the rangefinder on my M8.

[jlm]

just re-did the test with the rf set using the 50. the near is now 4" out.

 

does this make your eyes go buggy like mine?

 

carsten: i used a more distant target about 3/4 miles, nice truss and cables on a construction crane

 

jm

[innerimager]

OK Joe, I'll go it on my own. I happen to have an old rigid 50 summicron that should fit the bill perfectly. And the timing is great, I just received a replacement M8 that is in need of alignment. I considered sending it back as I didn't feel comfortable with the method already posted in the forum before, this one has a clear technique that, perhaps, even I can execute. Thanks again....Peter

[carstenw]

John, it sounds like you may have a near-far mismatch. By the way, there are two ways to approach this:

 

- match the rangefinder to your lenses.

- match the rangefinder to the proper setting, and fix lenses.

 

If you can't get the first to work for both (all?) your lenses, you will have to do the second. In that case, it may pay off sending the M8 away too, but that is your call. To do the second one, you do need a known good lens. The easiest way is to take your lenses to your dealer and try them out on a known good camera, if they have one.

 

If you do indeed have a near-far mismatch, ie. they can't both be correct at the same time, then the second rangefinder adjustment needs tuning. I have a long-ish thread about how to do this, but it is harder than tuning the wheel, and you'll want to at least consider having it done by Leica N.J.

[jlm]

I also called Leica NJ. the only tech there who does RF adjustments is... guess where...in Germany. he will be back Wednesday and I am personally showing up with camera and lenses in Allendale

[Tony C.]

I want to buttress what Carsten has said: use a celestial body for the most reliable infinity focus adjustment.

 

I first adjusted my M8 using a sign which was about two hundred yards away. I got decent results, but noticed someone on a much earlier thread who brought up the same point that Carsten has just made. I chose to re-adjust at night using a bright star, and found that the focus had in fact been off. Since that adjustment, I have found that my lenses focus very accurately.

 

None of this is meant to take anything away from the other aspects of Joe's interesting approach, but I would agree with Carsten on the importance of using a very distant object.

 

Regards,

 

Tony C.

[Shootist]

I also called Leica NJ. the only tech there who does RF adjustments is... guess where...in Germany. he will be back Wednesday and I am personally showing up with camera and lenses in Allendale

 

Well lucky for you for living in NY state not that far from NJ. Good luck, hope it all works out.

[jlm]

any thing I should ask those guys? heh, heh

[Englander]

@Carsten and Tony,

I absolutely agree that stars on a clear night are the best! I was indicating 1/4 mile as a minimum because so many seemed to be using a few hundred yards to make their adjustments.

@JLM,

I tried the interative approach with the lens on and off at first, but it never produced the kind of results I got with the focusing mount and a very distant object. Bringing the split image into alignment when using the focusing mount is quite clear and smooth instead of a little now and then a little more and then a little back. I think you need more than one magnifier, too. Also, the change in the precision of the near focus that you got already is indicative that you can probably do better. Try the stars tonight or a very distant light. Go for as much precision in adjustment as you can and then see whether the new adjustment produces better results with all your lenses. Might save yourself the trip to NJ. But if you go, I would be interested in hearing any insights. As I said, the lack of accuracy when I got my M8 back from NJ was the reason I bothered trying to adjust it by myself.

 

Joe

[carstenw]

Joe, 1/4 mile *is* a few hundred yards, 440 to be exact

[jlm]

joe: i was able to adjust using 50mm mount w/o the element, but i also found a bit of slop in the system. i would adjust, looking at the split image, then flick the roller a bit to get it to settle in, run the lens of inf and back to take out any slop in the action.

I only have the one magnifier, but might see if I can rig up something with a loupe. it is crazy to have to go through this, make me yearn for my rollei or the old blad. hard peeping through that little hole is nutty.

 

when I go to jersey (only about 45min away), I'm bringing my test sheet and a tripod.

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[Englander]

John,

I agree. I get blurry eyed, too. I cannot remember ever having heard of so many rangefinders being out of adjustment; and when one goes out while you already have it, well, there seems to be more changes to the finder assembly and adjustment than simply the change to the allen screw on the roller. I wonder if the test and assembly equipment is still based on the .72 finders and doesn't take into account that even though there is a REDUCTION in finder magnification there is typically a tremendous INCREASE in the magnification of the final product? The combination has got to really put stress on the precision of the adjustment of the rangefinder.

 

The slop in the system that you describe sounds like the tension spring is not forcing the roller cam against the lens. Its resting position should be tightly against the lens cam and if it doesn't go there all the time, ie if there is slop, then that might be part of your problem: not actually a rangefinder focusing misadjustment but a loose spring assembly. I hope NJ will help you while you wait and that the wait is only a short one.

 

Joe