How to precisely tune your rangefinder in 15 minutes or less

[billh]

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.... I just received a replacement M8 that is in need of alignment....

 

That, and the number of people excitedly inhaling the new way to adjust these things reminds me of the early 1900s when it was more important to know how to fix your car than to be able to drive it well.

 

I don’t know how many M8s are out there, or how many of those suffer from focus issues, but I can’t help but think there would be considerable demand if Joe or Mark conjured up some device we could use to recalibrate the focus accuracy. I hope, whenever mine returns from Germany, it is focusing correctly, but I really do not expect that to be the case.

 

Bill

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[Jamie Roberts]

Something else for John Milich to make, perhaps?

[Cindy Flood]

Joe,

Would you please elaborate on how I get the lens cell out of my 50 summicron? I think I can handle the rest.

Thanks.

[Englander]

Cindy,

It simply unscrews. Holding the lens mount in your right hand, use your left to turn counter-clockwise. Do not grab the aperture ring with your left hand, hold by the front of the barrel. In the old days, the summicron lens cell was used as an enlarging lens for murals and in the focusing bellows. The 90 Summicron, two generations ago, also was used for macro on the bellows and in the visoflex. The front cells of almost all the lenses longer than 50 up thorugh the 1970s could be unscrewed and used with reflex adapaters.

 

Joe

[ns_ng]

That, and the number of people excitedly inhaling the new way to adjust these things reminds me of the early 1900s when it was more important to know how to fix your car than to be able to drive it well.

 

I don’t know how many M8s are out there, or how many of those suffer from focus issues, but I can’t help but think there would be considerable demand if Joe or Mark conjured up some device we could use to recalibrate the focus accuracy. I hope, whenever mine returns from Germany, it is focusing correctly, but I really do not expect that to be the case.

 

Bill

 

Hi,

 

My M8 had to go back to Germany after I found out it had focusing issue. Photos taken at 1.4 and 2.0 at 3-4m. were not in focus. I used 4 of my lenses, 35 1.4 Asph, 35 2.0, Noctilux and 90 AA for testing and every one had focusing issues. I have heard there are a number of M8s with similar focusing problems.

 

After 6 weeks, the M8 came back and the focusing issue has been resolved, except with the Noctilux. Even with the 1.25X magnifier, focusing has been inconsistent at f1.0. I guess the 0.91X viewfinder in the M3 is still the best choice for focusing the Noctilux at f1.0.

 

N.S.

[rvaubel]

 

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

 

Some of the RD1s had backlash inherent in the rangefinder mechanism. If the pivot points are sloppy, there is really nothing that can be done to get an accurate system. The Leica mechanism is of sufficient quality that this is the last thing I would look for. But Dan Goldburg found a few RD1s that could not be adjusted properly because of excessive overall backlash. It is relatively easy to check for although I've never even done it on my M8 (which focuses perfectly, by the way).

To check for backlash simply remove the lens and press a little on the roller to move it just a bit. Now observe the relationship of the displacement of a vertical image in the rangefinder. Now wiggle your finger a little but not enough to move the image. The roller should not move at all, not even a thouthanth. Continue fussing around. Any movement of the roller should always result in a movement in the rangefinder. They should be 100% linked. If there is backlash you will see it. If you see it I would be very very surprised. If you see it you are also screwed since there is nothing that a non-Leica tech can do to fix it. Actually maybe DAG could fix a Leica but wouldn't try it on an RD1 after some initial attemps.

 

Rex

[wlaidlaw]

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I may have missed it on reading through this thread but how would you know if the old Summicron you use for this technique is accurately collimated to the correct back focus distance. Surely all you doing in this exercise is tuning your M8 to an old Summicron, which may or may not be correct. For example at some time in the past, someone might have removed or added shims to get it to focus better on a Konica Hexar. This is a point I have made on a number of posts. What we need to be able to do or have done is our M8 rangefinders tuned to a standard. Perhaps if JM could make a bayonet mount with a fixed cam point at infinity, that would be the easiest solution. As was suggested for the old Summicron, three or four M8 owners could have one between them. The problem with doing a super accurate standard adjustment is, of course, we might then find all our lenses needed to go back for adjustment - oh well.

 

I too have found that the infinity point drifts slightly over time and given how easy it is to move my cam with a 2mm hex wrench, I am not surprised. I always use my Elmarit-M 90 to tune infinity, so it is not a variation between lenses. I have found the edge of the moon is the easiest infinity point to use, being much brighter than a star.

 

Wilson

[Cindy Flood]

Joe said: Cindy,

It simply unscrews. Holding the lens mount in your right hand, use your left to turn counter-clockwise. Do not grab the aperture ring with your left hand, hold by the front of the barrel. In the old days, the summicron lens cell was used as an enlarging lens for murals and in the focusing bellows. The 90 Summicron, two generations ago, also was used for macro on the bellows and in the visoflex. The front cells of almost all the lenses longer than 50 up thorugh the 1970s could be unscrewed and used with reflex adapaters.

 

Joe

Thank you, Joe. It came apart with just a little pressure once I knew exactly what I was supposed to do.

[Englander]

Let me revise the distance I initially suggested. I said "at least" one-quarter mile and really, as noted above, using a celestial body would better satisfy earthly concerns about infinity. A star using coincidence or, better, the moon using split image, is quite clear and easy to confirm, easier in fact than a telephone pole at more than one-quarter mile. I still suggest using multiple magnifiers to increase attainment of accuracy, but one is much better than none!

 

@Wilson, I do not suggest using the lens mount for close focus or back-focus adjustment. I suggest it for infinity adjustment. And, yes, using an actual focusing mount without a lens cell is a surrogate for a real standard. I agree with both you and Mark Norton. But I really think it is more than acceptable for a number of reasons as long as the mount and cam have not been damaged. My primary reason for the suggestion is that Leica spent a lot of time making the focusing mounts and cams very accurate and they tuned the lens cells to the mounts on those lenses where the cells are supposed to be removable (and on others, too). The supposition, then, is that the control was very high for infinity settings on the focusing mounts since the lens cells would be moved forward and backward in the mount itself using shims to accomplish perfect optical infinity for the lens. In the old days, not only was the actual focal length and any shim depth written on the barrel of the lens cell, but also the calibration certifier’s signature or initials were scratched onto the part of the barrel that was deep within the assembled lens. Any shims were placed between the lens cell and the mount, the mount it itself was not shimmed. 50mm Summicrons up to this last mechanical iteration with the integral lenshood could all easily have their lens cells removed, so the unit doesn’t need to be all that old and could serve as a more than acceptable lens in daily use.

 

After having aligned four more M8s using the method I described and having them all accurate at infinity, they all produce close focus accurate to within 2mm at 0.7 mtr. So, I really do not have any qualms in suggesting that --if the close focus mechanism has not been fooled with--close focus will be brought into accurate focus as long as the infinity is PERFECTLY adjusted. The samples I posted earlier were NOT made with the lens (lens mount) I used for adjustment, they were with the lens available with the least depth of field. The adjustments seem accurate and painless enough and were perfect for at least 5 or 6 lenses (including a 35/1.4 ASPH) across 4 different cameras. When handed to me, all of the cameras were said to be “spot on” for infinity and all of the lenses were said to have problems with close focus. After adjustment, infinity really was “spot on” and none of the lenses had any close focus problems. It is very possible that part of the trouble a lot of people have had in adjusting their cameras for accurate close focus has been because what they accepted as “spot on” for infinity wasn’t really accurate enough. I do realize that since so much hand assembly is required with the range finder that there is a very real possibility of the near focus being wrong when the unit leaves the factory, but I also propose that perhaps some really serious attempts at adjusting infinity might help a majority of close-focusing problems. If this method brings three out of four of your lenses into accuracy, then it really is likely that the fourth lens needs help from the Doctors in Solms.

 

Joe

[harmsr]

Joe,

 

Nice post.

 

My advantage is that I had an M5 which had been adjusted perfectly by both Sherry Krauter and Ernst Hartmann. So, I checked all my lenses against this M5 as a master. It basically said my 35 Lux was out and so was my 50 Lux. The 28 Cron was good out of the box. The 15 CV was good out of the box. My 75 Cron & 90 Elmarit were sent to Leica in NJ for coding and came back perfect.

 

The 35 Lux should be on its way back from Solms as it had the dreaded focus shift ( I showed and discussed this with Stephan Daniels at PMA. Leica in NJ said it was not just a simple shim issue, but was with the internal elements so would have to go back to Solms. I'm keeping my fingers crossed.)

 

The 50 Lux is just slightly towards the backfocus side and goes a little past infinity. It will also go back to Leica in NJ, as this should be an easy tweek. (no focus shift due to aperture)

 

I sent my M8 to Leica NJ for rangefinder tweeking, as it was also just slightly out in the vertical. It came back perfect, in all respects.

 

Sherry also stated the standard for infinity is really "at least 30 miles". My initial thought on the return of the M8 was that my lenses were going past infinity, which was not true. Using a group of cell towers on a mountain about 5 miles away, was not truly infinity. Using a magnifier and the stars, the M8 and my other lenses due truly stop at exactly infinity. They also focus correctly at all other distances.

 

Best,

 

Ray

[wlaidlaw]

Joe,

 

Given what you say, I would agree that the removeable cell Leica/Leitz lens bodies would seem to be as close to a standard as we can get. I am afraid I suspect that tolerances in the 1960's and 70's were more closely adhered to and inspected than nowadays. Maybe also the pride of workmanship was greater - today I would guess for a lot of Leica workmen, it is just a job and roll on 5 o'clock or the week-end.

 

I have re-tweaked my infinity tonight using Jupiter as my target (400+ million miles should be far enough), a 1.25x magnifier and another non-Leica magnifier. It took about 12 lens on, lens off adjustments before I was 100% satisfied. The two Zeiss lenses (21 and 35 Biogon) and the Elmarit-M 90mm agree with each other precisely. My new Elmar-M 50 Collapsible seems just a tiny fraction out but given that it is an f2.8, probably not enough to matter and to warrant a trip back to Solms. Interestingly, it was one of the new, unused but uncoded Elmars, sent back by a dealer to Solms for coding before sale. Makes you wonder how accurate the coded bayonets are. I had changed the bayonet on my Biogon 21 from a 24/35 bayonet to a 28/90 bayonet but the infinity seems as good as original. The standard of finish on the lens body back mount and the bayonet was very high and the register excellent.

 

Wilson