Dim RF patch AFTER new mirror...

[olliewtf]

Fully rebuilt my IIIc last month, including changing the rangefinder mirror - though the results were disappointing. the contrast wasn't really that much better. Im sure I put the mirror in the right way around, not that that should have this much of an impact.

What else could be the cause? Or could the replacement just not be that great? An old Zorki I have lying around is 100 times better.

I did clean the other optics of the finder too. mirror bought from nobbysparrow.

thanks all!

 

[Bill Clark]

My recommendation, send it to a person who has the knowledge and expertise to work on your camera.

The way I look at it, at my age, each minute I live is a greater percentage of what I’ve got left here on earth.

Working on some of this stuff is like a gent I know who rebuilt the transmission and rear end on a Model A Ford and, when he was done, fired up the old coot and discovered he had three speeds in reverse and one to go forward. Tear down and do it again!

At any rate, if you enjoy doing this sort of task then go for it.

 

[Mr_Flibble]

Hmmm, contrast should be better or at least just as good as the Zorki.

Maybe the beamsplitter isn't a 50/50 reflection/transmission mirror.
But I doubt NobbySparrow would've sent you the wrong material

Is the diopter adjustment working?

 

[olliewtf]

The screw was missing that held the eyepiece to the rangefinder assembly, so as a quick solution i glued it - so it does work but the way there wasnt the most straightforward.

One thing that is missing is the cap that covers the end of the housing where the mirror pulls out - i figured it wouldnt make any optical difference as the cover keeps things dark.

ill most likely get in touch with nobby sparrow and see what he thinks. he kindly gave me a free mirror as a spare so I can always try that. The only thing I can imagine to be wrong is the mirror. strange.

 

[olliewtf]

So im wondering - the rangefinder prism - thats the prism behind the first viewfinder closest to the lens, and I presume the one that moves via the arm. Is this also silvered? and could this being worn also cause a dim patch?

Hence why replacing the splitter mirror had little effect as the dim-ness was caused by the prism?


Feel free to point out ive got it very wrong!

I also hear the prism is very difficult to replace - so if I do need to replace the rangefinder, where would I get one?

 

[xayraa33]

So im wondering - the rangefinder prism - thats the prism behind the first viewfinder closest to the lens, and I presume the one that moves via the arm. Is this also silvered? and could this being worn also cause a dim patch?

Hence why replacing the splitter mirror had little effect as the dim-ness was caused by the prism?


Feel free to point out ive got it very wrong!

I also hear the prism is very difficult to replace - so if I do need to replace the rangefinder, where would I get one?

You can buy a parts IIIc and change the whole RF assembly in one piece and maybe put the new 50/50 mirror on it instead, no guarantee that the parts camera will have a good usable RF unless you get to inspect it before you buy.

Another solution is to leave the IIIc the way it is and use it with slow wide angle lenses where super accurate focus is not critical, maybe slap an orange filter on the RF window to increase RF image contrast.

Repair techs like DAG could fix your IIIc but it would not be cost effective unless it is a valuable war time stepper IIIc

Give Oleg at OK Cameras an enquiry by email, maybe he has a way to fix your IIIc for an affordable price.

http://tunnel13.com/blog/leica-iiif-beamsplitter-replace/

Note: Have you checked if the rotating wedge prism in the RF geometry is clean ?

 

[richardHaw]

1: clean the PRISM very well on all 3 vertical sides

2: replace your mirror and make sure the right side is facing front

3: clean the small lenses very well

4: use a blue permanent marker and lightly colour the window of the RF (right-most) so it's tinted. chances are its now too clean and the brightness is blowing the reflection off

5: never glue anything just to make it stick, find the right screws for them

PS: mr Kuramochi's mirrors are great. I ordered one from him yesterday, i am his regular customer. i call him sometimes and have custom sized mirrors cut to my specs.