M Body RF Adjustment

[boojum]

OK, you all may know this already. But for the one or two folks like myself who do not, here is Overgaard showing how to adjust the distance measurement in the Leica M body RF.

 

[yossi]

This is a nice video, but potentially misleading! There are two screws (A and B as shown in pix below) in a Leica M camera for focusing adjustment and they will affect one and other.



In the above video, he only adjusts screw (B) that would move the "infinity" nearer or further away, but that would also affect the near focusing accuracy at the same time!

The proper way as I understand is to tweak the pivot point (A) and then (B) again, INTERACTIVELY (in a way, it is two degree of freedom); and finally/hopefully the RF can achieve focusing accuracy for both near and far object.

Ceveat: I am just a Leica shooter and not an expert repairman. So any expert sharing more details on this RF focusing adjustment is most welcome.

 

[boojum]

This is a nice video, but potentially misleading! There are two screws (A and B as shown in pix below) in a Leica M camera for focusing adjustment and they will affect one and other.

View attachment 4846702

In the above video, he only adjusts screw (B) that would move the "infinity" nearer or further away, but that would also affect the near focusing accuracy at the same time!

The proper way as I understand is to tweak the pivot point (A) and then (B) again, INTERACTIVELY (in a way, it is two degree of freedom); and finally/hopefully the RF can achieve focusing accuracy for both near and far object.

Ceveat: I am just a Leica shooter and not an expert repairman. So any expert sharing more details on this RF focusing adjustment is most welcome.

I understand what he did. I did not know that it would affect the whole focus range, as if it were sliding back and forth on a tray. But there it is and some resident Djinn will hopefully chime in and clear all this up. I suspect that you have it right.

If there is a Q&D fix for focus that would be great.

 

[Coldkennels]

I understand what he did. I did not know that it would affect the whole focus range, as if it were sliding back and forth on a tray. But there it is and some resident Djinn will hopefully chime in and clear all this up. I suspect that you have it right.

In theory it depends on what's shifted and what needs adjusting.

The easiest way of understanding a rangefinder mechanism is picking up a FED or Zorki and tinkering with it. On that system, the adjustments for both points of focus are very easy to see, adjust, and understand - one is a screw near the RF window, the other is the wedge-shaped cam follower.

When first calibrating the rangefinder (or converting it from the Soviet standard to the Leica one) you'll need to repeatedly move from one end of the focus range to the other. You'll dial in the infinity alignment by adjusting the position of the prism in the rangefinder via the aforementioned screw, then go back to the close focus at one meter and find that's far out of spec. Then, upon adjusting the close focus - which is done by physically rotating the cam follower so the wedge is slightly further in or out, therefore changing how far the arm will move as the lens focuses - you'll find the infinity is out again because the arm is now in a different position when the lens is at its closest position to the body.

So, adjust the infinity alignment until that agrees, then go back to one meter, and what do you know? That's out of spec again - but less than it was on the first pass. You have to repeat this process until both ends of the scale agree, and the first time I did it back in 2010 it felt like it took me HOURS. Now I can do it within ten minutes or so. Maybe less.

The good news is that usually any drift in the RF calibration is usually just at one end of the scale, and often times tweaking the calibration at infinity is enough. I've not done it on an M myself (never owned one until last month), but I've heard that with M mount cameras, the close-focus adjustment is supposedly pretty tightly set (to the point it can be an absolute bugger to adjust if you need to), so often it's only the infinity end that needs adjusting.

The problem is that without really understanding how the system works and what is happening, you can adjust the infinity end of the rangefinder mechanism only to find the real issue was the close-focus end (that's pivot point "A" in the photo above, which basically operates the same way the FED/Zorki cam follower does, only in a slightly less-obvious way - it controls how far the arm can/has to move), and all of a sudden nothing is sharp at 1m.

Add in the variables the lens brings to the table (is it optically perfect? Does it back focus at any point in the focus throw or aperture range? Is the rangefinder cam built and operating as it should?), and there really is no "Q&D fix" - just things that might work if you're lucky.

 

[Godfrey]

Hmm. I agree with Yossi ... Thorsten didn't really do the adjustment entirely correctly.

My old local camera technician finally retired a couple of years ago and returned to Germany to be with the rest of his family (he'd been living/working in the USA for about 40 years, and was 84 when he returned home!). But some years before that he taught me how to do a complete collimation and calibration of a Leica M rangefinder ... he was just starting the job when I stopped into his shop one day to say hi and invited me to stay and learn the procedure. I've done it once since on my own ... It was tedious but not hard.

Fred: "Ja, this is always a little finicky but not hard. Of course if you don't bang your camera into things, you almost never have to do it."

I've evidently taken his advice since I've only had to collimate/calibrate the rangefinder in any of my Ms twice since 1973. At that frequency, I just send the camera off for a service. I'd probably be more skilled at the task if it needed doing more frequently... I use my cameras a lot, but I don't bang them around if I can help it. 😉

G

 

[Coldkennels]

Fred: "Ja, this is always a little finicky but not hard. Of course if you don't bang your camera into things, you almost never have to do it."

I've evidently taken his advice since I've only had to collimate/calibrate the rangefinder in any of my Ms twice since 1973. At that frequency, I just send the camera off for a service.

This is the bit that always concerns me for my own cameras, and is the real reason I learned to do this myself.

I've seen so many people over on Reddit talk about how they sent their Leica off to DAG/Sherry/YYE etc. only for it to come back and the rangefinder is still out of alignment.

Have you seen the way a lot of couriers treat packages?! Slap all the fragile tape on that you want, that camera is still being thrown around all over the place.

The very first thing I've done whenever I've received a rangefinder through the mail is check the calibration - and when I've sold them on eBay I've said the exact same to the purchaser. I don't know why this doesn't occur to more people - "I bought this via the internet and it was delivered to my house but I'm scared of taking it with me when I'm riding a bike in case it knocks the rangefinder out." If it survived USPS, it can survive a bike ride!

 

[Godfrey]

I pack photo equipment for shipment with about 3 inches of vibration/impact absorbing stuff all around it, double boxed. Never had one come back out of adjustment, even if the outer box was all bashed up. I've also had a Leica M in the tailbag of my motorcycle, the trunk of my car, or in my sling bag on the bicycle for many many many miles ... always properly wrapped in some kind of absorbent stuff ... and I've never had one go out of adjustment that way either.

In my experience, it seems to take a good solid "thump!" on the body to cause the rangefinder adjustment to shift. I bet it's more easily disturbed at some angles of being struck than others, but it's not something that should fall apart easily unless something else is amiss. ... The M is pretty darn robust, it's not some fragile piece of china.

G