I need a part from a 2.0/50 Pancolar

JohnBar · Joined: 21 Jun 2012 Posts: 581 Location: Liverpool

I am restoring a botched amateur attempt at a CLA on a Pancolar, I have discovered after opening the lens that the spacer ring is missing. So the lens will only go to about 5m at the infinity symbol.

This spacer ring is the one that sits under the second inner most slotted ring when you look behind the nameplate ring. It is the only spacer ring used in the construction.

If you have a donor lens that yoiu use for parts then perhaps you could sell me this part.

Contact me off board if you have this ring.

best,
John

Lightshow · Joined: 04 Nov 2011 Posts: 3666 Location: Calgary

A machine shop should be able to turn a spacer for a few bucks, all you would need is the dimensions.(I would get it a bit too thick and then file/sand it down to the needed dimension)

Gertjan · Joined: 06 May 2009 Posts: 18 Location: Netherlands

This spacer ring was used at the factory to adjust infinity focus.
They had rings in a range of different thickness, and choosed the best one.

As this ring is pushing the entire optical block forward, adding a ring will give you an even shorter max. focusing distance.....
So, something else is wrong with tour lens too. Probately the focusing helicoids are in a wrong tread.
Split the helicoids, and find the tread that gives you focusing past infinity. Than you can adjust with a spacer.

Measure the tickness needed and have a few rings made, the measured size, one 0,1mm thinner and one 0,1mm thicker.
Than pick the best.

I had to do this when I adapted my Exacta mount Carl Zeiss Jena lenses to EOS. (The adapters were too thick)
For real good infinity adjustment I needed rings with 0,05mm difference in thickness

The sizes of my original ring: thick: 2,35mm, outside diameter: 40,9mm, inside diameter: 38,6mm

I include a sketch I made for myself to understand the focus adjustment.
Text is unfortunately mostly in Dutch, but I think you will understand. (left is the front of the lens, and right is the back)

Good luck, Gertjan.

JohnBar · Joined: 21 Jun 2012 Posts: 581 Location: Liverpool

Having one cut is always an option and many thanks for the dimensions.

I am tempted to make one by soldering a hoop from copper wire of the correct AWG. No one will see it and as long as it works ....

Gertjan · Joined: 06 May 2009 Posts: 18 Location: Netherlands

I think that your idea of using Copper wire is very clever!
Maybe there is no need to solder the ring, as it will be in a cavity, so the Copper wire can't go anywhere.

But still you first have to find a way to move the optical block back towards the Camera to reach infinity focus.....
As you mentioned "a botched amateur attempt" I think the chance is almost 100% that the multi-threaded focus helicoid is in a wrong tread.

Regards, Gertjan

JohnBar · Joined: 21 Jun 2012 Posts: 581 Location: Liverpool

Thanks for your kind words.

Regarding the helicoid - it is most likely only one thread from the correct starting position.