dust spots on M2 RF patch - is this an easy(ish) DIY project?

[yossarian123]

I recently came into possession of an M2 - it's in amazing shape except the RF patch has some dust or spots on it. Contrast is definitely lower and it's something I want to get fixed. I've been told that the M2 recently had a CLA so I don't really want to send it in for another. Is cleaning the VF and patch an easy job, assuming that I have the clamps and spanner wrench required to pop the top plate off? Would cleaning the RF patch involve much more than removing the top plate or would it require removing the RF assembly?

And since I know I'll get the inevitable response - yes I really should send it in to a skilled technician but as long as it's a simple repair I want to try this myself.

 

[mooge]

shouldn't be too difficult... Dust spots in the RF patch will be from dust on the lens of the framelines mask.

Dunno about cleaning the rest of the viewfinder though; when I tried it, nothing happened. Try not to scrub too hard, it might rub away the coatings or shift elements and misalign the RF. Oh and not everything in the RF is accessible without more disassembly. I think. it's been a while since I've messed with the RF mechanism (and it's not fun)...

 

[Landshark]

If the dust is within the rangefinder itself a cover may have to be removed but not the RF itself.

There's a screw at the top of the lens mount that has to be removed, It's the seal that people refer to when they say "L seal intact" if you remove it, it will be noticed.
You're aware that there are flexiclamps needed to remove the cover.

Some of the top covers are incredibly tight and have to be encouraged to come off.

Collars on both synch contacts, ring under RW knob, eyepiece, collar around shutter release button. On the M2 the frame counter index, the counter itself And the screw at the top of the lens mount.

 

[Vickko]

The RF mask and optics are a tricky spot to get to.
Here's a pictorial of it

See the black mask in the middle, that is what you need to get to. It is a tight spot. Sometimes just blowing the area with air is enough to dislodge the dust.

 

[yossarian123]

Wow, thanks for the info. I'm going to give this a shot - at least pop the top off and see what it looks like inside. This is for an M2 - does the little silver dot by the frame counter window need a special clamp or will the regular set (from micro-tools) cover it?

 

[Sparrow]

that schematic looks a lot better than the reality, it's inside this

 

[MikeL]

Yossarian, once you get the top plate off, take a look at the top. You'll see two screws that hold the frameline mask unit in place. Vics' schematic is from a digital M, and you can't see them on Stewart's photo. If you find the M2 manual and Tomosy guide, you'll see what I'm talking about.

I'd try and blow off the dust as mentioned, but you may need to remove the unit. It is engaged by a connection that controls the masks and parallax. It has been awhile since I cleaned one, but I remember there was a step that required caution when removing and then re-inserting the mask.

Edit: Here's a page showing the brass mask unit and two screws I was talking about: M2 with RF patch anomaly

 

[mooge]

just my opinion but... if you're going to go in just to look around, try not to mess with things too much. I wouldn't remove the framelines mask (why??? you shouldn't have to...) or remove the RF (you'll have to realign it if you do)-- it's more work and more time your camera is out of action. And there's always the chance that you might goof and get stuck (know your limits, as they say).

But don't let what I say discourage you from diving in if you want to learn how the M2 works. It's not that complicated. (but it can be a pain to get things realigned, in my experience-- the slow speeds escapement and the RF, for example...)

And I'm pretty sure that the framelines mask is the only place that you can get in-focus dust spots in the RF-- think of it this way; the framelines and RF patch are sharp because they're in a plane of focus; the other elements... not so much-- like having dust on your glasses; you can't really see it most of the time.

and there's a couple M2 repair manuals on the internet somewhere. One is for the M2-R military one (KS-14?) and another was written for some magazine. you should be able to search them up pretty easily...

good luck!

 

[Sparrow]

... I just cleaned what I could get to easily, and vacuumed the dust off ... keeping the dust off while reassembling is the hard part. You will probably have to replace the clear tape (at the right of the pic) and re-glue the cover thing ... you can see the dry old rubber based glue in the centre, this thing