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M10P range finder piece fell out...


KFo

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Back in November I had a range finder malfunction during a trip.  I continued on and had it repaired when I arrived home.  Everything has been fine since then until...

Yesterday I went out to reshoot some things in better light.  First scene, I started focusing and noticed the focus patch wasn't moving.  I popped the lens off and found the same condition as before.  The range finder was only operating at very close distance (˜4m and closer).  Disgusted, I walked home and on the way decided that I'd open up the camera myself and figure out what was going on.

A half hour later I had the M10P top cover off and was playing with the range finder mechanism.  Much to my surprise I found a tiny optical component ( pictured below - it's about 5 mm on the long edge) loose jamming the mechanism.  Without further disassembly removing a couple of more PCBs and ribbon cables I couldn't see where it may have been located.  I removed it, it was floating around loose anyway, and reassembled the camera.  Testing the rangefinder I find that it focuses accurately at all distances (as it did before), however, it seems that the horizontal and vertical alignment of the focus patch are now perfect and the image in the patch is ultra sharp whereas before it was neither.  

I've been trying to find a good assembly drawing of the rangefinder mechanism online, but everything is pretty poor and lacking details.  No good images of the mechanism either.  The most informative diagram so far is this one.  It seems possible that I found the "optical wedge" (as labeled in the linked diagram) laying loose which is part of H and V adjustment of the patch.  This might explain why the alignment is now perfect.

Any input on this matter?  Aside from "send it to Wetzlar which I'm not inclined to do."  I'm inclined to continue using the camera with the little optical wedge in a labeled baggy in the camera stuff drawer.  Was this HV adjustment an addition to address something that is no longer relevant?

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Edited by KFo
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Very intrigued by your story and picture! I cannot imagine that this piece of twisted and damaged metal was an essential part of the focussing mechanism of your M10. Now that your rangefinder is working to your full satisfaction I wonder even more!

Could it be Leica used this to align your rangefinder when in service? Like a bad chirurgeon they forgot to take it out before closing the body (!). Enjoy your camera!

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1 hour ago, Maarten said:

I cannot imagine that this piece of twisted and damaged metal was an essential part of the focussing mechanism of your M10.

Metal? It is a glass (or plastic) prism. 😁

@KFo - check a couple of things for me. Do either your 1) viewfinder framelines, or 2) the red LED metering readout in the viewfinder, look any different now?

Because this looks a lot like the semi-periscope prism that projects the metering LED (red numerical display) image, from its location on the flexible printed circuit board, up into the bottom of the viewfinder "view." And your description of the size also matches that.

But given the fact the frameline slits are now also back-illuminated by an LED, it may come from that optical system.

EDIT: also, just for grins, have you checked the smaller rangefinder window on the front of the camera? Does it still have its glass windowpane - or is it just an empty rectangular hole?

BTW, the M3 RF/VF was only ever used in the M3. When the M2 was released (with 35mm framelines), the whole system was redesigned, and has been used ever since (with subsequent revisions as well - M6, and then MP, and then M10/11).

This is a view of the more recent layout, with fewer right-angle bends in the light path (from the M6, I believe)

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Edited by adan
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@adan lol, yup the rangefinder window still there!

It is really strange, frame lines are all there and working correctly.  The metering and shutter speed display is also there and working fine.  To my eye they are the same in appearance as ever.  Bear in mind though that I never really study them, it's just a quick glance for me, often not even directly at them - more of a peripheral awareness.

The only thing that looks different is the focus patch which ( and I often pay attention to 🤦) appears sharper and brighter.

Edited by KFo
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1 hour ago, adan said:

...snip....

BTW, the M3 RF/VF was only ever used in the M3. When the M2 was released (with 35mm framelines), the whole system was redesigned, and has been used ever since (with subsequent revisions as well - M6, and then MP, and then M10/11).

This is a view of the more recent layout, with fewer right-angle bends in the light path (from the M6, I believe)

Prior to the M2 was there an adjustment for H&V on the focus patch?

Edited by KFo
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6 hours ago, KFo said:

The only thing that looks different is the focus patch which ( and I often pay attention to 🤦) appears sharper and brighter.

So tell us all how we can make this part fall out...... 😁

6 hours ago, KFo said:

Prior to the M2 was there an adjustment for H&V on the focus patch?

I'm sure there was - it's a critical part of keeping any RF aligned and happy.

The same "cylinder of little lenses" is still visible in the later diagram, between the long prism, and the frameline mask - just canted backwards to align with the more diagonal light path (red arrow).

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38 minutes ago, adan said:

So tell us all how we can make this part fall out...... 😁

 

I was going to ask the same thing! Question is, brighter and sharper relative to what? Before the piece was potentially blocking a light path, or while it was?

Edited by charlesphoto99
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2 hours ago, charlesphoto99 said:

I was going to ask the same thing! Question is, brighter and sharper relative to what? Before the piece was potentially blocking a light path, or while it was?

It is brighter than before.  Relative to itself...

It may have been falling out for awhile degrading the focus patch quality.  I don't know for sure.

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6 hours ago, KFo said:

It is brighter than before.  Relative to itself...

It may have been falling out for awhile degrading the focus patch quality.  I don't know for sure.

May be time to compare with factory default RF and see if that thing fell off from your M10 is actually some kind of glass piece that dimmed the patch for other intentions 

 

this is getting interesting 

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Is it conceivable (however unlikely) that this was a part that was accidentally introduced during manufacturing? ie the technician dropped it, looked but couldn’t find it, figured it rolled under the bench or whatever, reached into the parts tray for another (the whole line can’t back up while a plentiful part is searched for) and got on with the build, but it had actually fallen into the camera..?

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Well, I remained puzzled.  I have a hard time seeing how some little bit of a prism or whatever this piece is comes loose, jams up the works, gets picked out, and still the camera focuses fine.

So maybe it fell in from someplace.  Although I've never heard anything rattling around.

This afternoon I put on my 90 Macro Elmarit-M in to double check focus...10m, 1m, whatever, right on the money.

Edited by KFo
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Very interesting. The piece could of course originate in some other part of the camera than the rangefinder mechanism or viewfinder, but if it's made of glass I very much doubt that this is the case. And if it's a piece that was dropped into the camera at the production line by mistake one might assume a similar piece to be found somewhere in the camera.

As already mentioned, the M3 rangefinder is very different from that of the M2 and later models but there have also been smaller modifications made after that (in addition to changes in VF magnification and addition of framelines). In particular, there were some changes affecting rangefinder patch flare in certain conditions. At some point this topic was discussed at least regarding the M6TTL, M7 and MP and, if I recall correctly, Leica had to revert some changes previously made, (re)introducing some optical part in the rangefinder. If the only function of this part is to reduce flare, the rangefinder would work quite well without it. Does anyone have more details on this change/addition?

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