Re: [Leica] DIY Rangefinder adjustments

[John Collier <jbcollier@home.com>]

If you persevere though the ridiculously long message I sent, sorry about
that, you will find that most in service adjustments just require tweaking
the eccentric screw that holds the roller onto the arm. The screw you
mention does adjust the vertical alignment of the rangefinder. Late M4-2 and
up have no screw there but require a special tool to make the adjustment.
Here is an excellent post from Jim Brick on that adjustment:

- --------------
It's about as long as a new wooden pencil. The handle part of it is a
little smaller than a pencil. It then tapers down to a shaft about the size
of pencil lead. Perhaps between .9 and 1.5mm. Machined at the end of the
very tiny shaft, is a slightly larger round disc, perhaps 2 to 3mm across
and 1mm long. Then sticking out of the far side of this little disc, out on
the edge, is a pin perhaps .7mm in diameter and .5mm long. These are
estimates, but the business end of this tool is teeny tiny.

You stick this tool through the M6 or M4-2 hole, there is a tiny hole, in
the RF mechanism, for the pin to insert into, the larger disk now operates
like an eccentric (hence the name of the tool - M6 RF eccentric). The RF
mechanism is at an angle so you have to push the RF lens coupling cam all
the way into the camera to bring the adjustment mechanism near straight in
order to insert it. You turn the tool very carefully, it rotates around the
pin, and the eccentric disc moves a plate which adjusts the vertical
alignment. Only the teeniest turn is needed. This is a very clumsy trial
and error procedure because it is difficult to leave the tool in while
checking the alignment and because of the angles on the mechanism,
sometimes it's difficult to get the tool out.

To make matters worse, new cameras have the adjusting plate lacquered in
place and it takes a large amount of force to break the lacquer seal for
the first turn, which of course, takes it way way out of alignment. But of
course, once broken loose, it is easy to adjust and the tiny tiny movements
necessary to bring it into alignment are difficult. Mainly because you
cannot feel if it has moved or not and you have to keep visually checking
the RF.
- -----------------------

> From: "Craig Roberts" <croberts@zoomtel.com>
> 
> John Collier kindly wrote:
> 
> "Here is a message from the archives:
> The three screws are almost exactly as you described. The third screw with
> the eccentric behind the rangefinder's arm....etc."
> 
> YIKES!!!  Many thanks...but I'll think I'll be sending my camera out, if
> necessary.
> 
> I would like to know, though....behind a chrome plated cover screw next to
> the viewfinder "diffuser" window on my M3 is an adjustment screw.  It seems
> to affect the vertical alignment of the coincident viewfinder images.  Is
> this correct?  Is this the same adjustment screw that's beneath the infamous
> "red dot" on an M6?
>