Shimming lens on Zorki 4

[wclavey]

I have a Zorki-4 that I am certain needs to have the lens shim adjusted. I did the procedure described by D_V_D_27 in the repair notes section... I aligned the RF adjustment to the markings on the lens to the actual distance measurements. So, through the rangefinder, and object at infinity aligns at infinity, 1 meter at 1 meter, 2 meters at 2 meters, etc.

But close up pictures (closer than 4-5 meters) are still out of focus with the lens at f8 or wider (and I have tried the same experiment with 3 other 50mm lenses... same result). So I put one of my Olympus focusing screens into the film gate and, voila, objects that are 1.5 meters away (actually measured) focus on the ground glass with the lens distance scale set to 4 meters.

So here is my logic. When the lens is set for 4 meters, it is closer to the film plane than when it is set to 1.5 meters. This means that I need to move the lens closer to the body, which means I need to remove some of the paper lens shims, right?

There are 2 paper lens shims in this Zorki-4 (in fact, there are 2 shims in all 3 Zorki-4s I have opened up...). It is hard to believe that removing 1 or both of these will make a difference... so is there some guideline about the shims? 1 shim = X% of a rotation of the focus helix or something like that? Or is there some other adjustment of the lens-to-body distance that I haven't found?

If anyone has any operational or experiential insight here, please provide some guidance. I'd like to not have to discover it all through Trial & Error, but I can.

Thanks, in advance...

 

[Spyderman]

Check the lens registration distance: distance from the front of the mount to the film plane = 28.8mm. This is the thing you shoul start with. If it's different, only then add or remove shims.

If the lens registration is right then the problem is in your lens(es).

 

[wclavey]

Update:

Thanks for the help.

I measured the distance as accurately as I could. By removing both shims, it is now 28.8 (or closer to it than it was before... it was well over 29 before adjustment). I had to then readjust the rangefinder to focus on infinity and adjust the cam to get the lens scale and the RF to match. From what I could tell on the focusing screen on the film gate, all 3 now look to be matched. I am ready for a film test.

 

[Spyderman]

Congrats 🙂 and happy shooting 😀

 

[DaveP]

Its necessary to fine tune the measurement. Check all four corners of the film opening,not just take a measurement in the middle of the mount.