Leica Carl Zeiss Jena 5cm F2 Sonnar, 1934, adapted to Leica Thread Mount

mcsqared

New Member
Mar 25, 2014
1
Brain
I got unscrewed, yeah....
it does has a very thin copper ring, should i keep it? it is so thin, i afraid to damage it.
 

BrianS

Super Moderator
Apr 3, 2013
124
Welcome aboard! Just saw this, been spending the last 4 hours debugging a device-driver...Lots of trial and error. Just like working on lenses, but you do more typing.

The thin copper shims are about 0.02mm thick, I use a very small screwdriver to work it over the threads. It is thinner than you really need for nailing the focus, you will probably be re-using the thicker shims and cutting some aluminum foil.

Any Jupiter-8 LTM focus mount will work. Most likely, you will need to swap the aperture rings as well. Remove the retaining ring, which is held in with a set screw, and take out the coupling screw that holds it in place. The later Black focus mounts are more reliable, have less slop in the helicals, and are easier to work on. The early aluminum ones with the Tab are usually better made than the 1960s aluminum J-8's.

FLICKR launched a "new-interface" and I think they took away the Bulletin Board protocol, force you to use html and post on facebook and others which I do not use. Unless it is hidden, I will repost the images here. It's too bad, Flickr is doing itself out of a lot of members.



So- I clicked on the "share" on the new interface that some idiot came up with, clicked on the "pin Icon", copied the code that was generated and took out everything that was outside of the "img" commands, and changed it from https to http.

Let me know if others can view it.

Stupid Flickr.
 

BrianS

Super Moderator
Apr 3, 2013
124


Retaining Ring, has a set screw.

Coupling screw for aperture ring.



Aperture ring off, ready for the J-8 rind- after cleaning all the old oil out!

 

BrianS

Super Moderator
Apr 3, 2013
124
while I'm at it...



The namering is held in with two set screws. these come out, the front element and front triplet come out. The rear doublet simply unscrews.



The black paint was coming off of the triplet and the rear doublet, I used a Black Sharpie to replace it. Works well.
 

BrianS

Super Moderator
Apr 3, 2013
124
And the finished lens with the "left-over" parts. I'll use the glass in the Jupiter-8 optics to repair another lens. The J-8 optic al fixture is a different shape and will not fit into the collapsible mount.



This lens is on it's way to a Leicaplace member.
 

mcsqared

New Member
Mar 25, 2014
1
And the finished lens with the "left-over" parts. I'll use the glass in the Jupiter-8 optics to repair another lens. The J-8 optic al fixture is a different shape and will not fit into the collapsible mount.



This lens is on it's way to a Leicaplace member.
I got it!!!!
Many thanks!

My comes with two very thin copper rings, do I need to reuse them? or should check the infinity focus first? if doesn't focus infinity, put the copper rings back?
 

BrianS

Super Moderator
Apr 3, 2013
124
Is that what my 1941 T Sonnar looks like?
That's the one! I disassembled it, gave it a full CLA- wanted to document the breakdown.

On the Shims- once the optical fixture is in the new mount, the lens must be shimmed for correct focus. This means new shims, which can be made from aluminum foil, old retaining rings, etc. The thickness is critical, this one's final adjustment was to within 0.01mm for the final. You can use the retaining ring for the aperture ring as a variable stand-off ring, unscrew it a fraction of a turn as required and then make a new hole for the set screw.
 

BrianS

Super Moderator
Apr 3, 2013
124
Took out the 1934 Sonnar today, and the Summar.

This is the Sonnar, wide-open at F2.



The red lighting is from the roof of the train car.

 

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