FSU Rangefinder path adjustment

Daimon

Established
Local time
8:46 AM
Joined
Jun 9, 2023
Messages
74
Question about rangefinder adjustement. But not a standard RF rotating window + adjustement screw.

I noticed that some FSU rangefinders tend to have a crooked rangefinder ghost image. Did some checking and culprit is clear - RF mirror is not aligned with beam splitter plane.

Any guidance on how to perform adjustement process?

Example from my Zorki 6 on how bad it can be :( (yes, it's not possible to calibrate RF at all on this camera using a standard method)

IMG_20231013_144654_443.jpg
 
Is there a big screw with a washer on the back of this prism?
If so I am guessing that is this securing it ... so you should be able to loosen it and adjust the tilt.
 
Yep it's there. But I'm more wondering about proper "process".

- main prism with beam splitter may have some tilt and it's not adjustable
- RF window prism has adjustable axis - by loosening 2 screws marked by red arrows it's possible to slightly skew axis itself
- then as you mentioned it's also possible to rotate prism itself by loosening screw on back (blue arrow)

IMG_20231013_120631_478~3.jpg
 
I would guess the two top screws would give minor adjustment ... and the screw in the back for major movement (which it appears your prism needs).
 
Ok so to make it clear there are 5 screws there but one is in the shadow :)
- 2 big marked by red arrows - those allow to move top plate effectively changing axis (i.e. changing ball bearing position)
- 1 big on the back of prism - marked by blue arrow - this should loosen prism itself
- 2 small these allow to fine tune prism axis (which is orthogonal to the axis controlled by red arrow screws)
 
Hmm, I cannot provide any experienced advise as I have never worked on a Zorki ... just guessing based on the images I have seen.
 
Back
Top Bottom