Jupiter-3 Focus Slop, culprit, and correction.

[Sonnar Brian]

I'll be posting another pictorial on Lubing an early Jupiter-3 on ziforums.com soon. I just rebuilt a beautiful 1953 KMZ J-3. Glass beautiful, focus action was really bad due to dried grease. Once rebuilt, the focus action was smooth- except for a 1mm play in the action. Basically, the inner helical would shift about 1mm before turning.

The culprit is the guide screw in the rail shown in this picture:

The head of the guide-screw in the slot is responsible for the annoying slop in the Jupiter-3 Focus Action.

I just replaced this screw with one from a later lens -I think from an I-61, ended up in my parts bin-, had a larger diameter head on it. PROBLEM SOLVED! Very nice and smooth action. The slop does not cause an error in focus, as the RF cam moves with the lens. It's just "annoying".

Photo's from the teardown and relube here:

http://ziforums.com/album.php?albumid=199

I will post a narrative thread under the ziforums projects forum soon.

 

[raid]

When you open up these lenses, Brain, they look downright super ugly! Then you actually use such lenses, and they turn from frogs to cute healthy looking princesses (I had to improvise since I prefer princesses).

 

[Sonnar Brian]

I just had to buy another 1953 KMZ J-3 after rebuilding Tim's!

 

[Sonnar Brian]

When you open up these lenses, Brain, they look downright super ugly! Then you actually use such lenses, and they turn from frogs to cute healthy looking princesses (I had to improvise since I prefer princesses).

Before Ultrasonic Cleaner

After Ultrasonic Cleaner:

I love my $35 Ebay Ultrasonic Cleaner! The zizzy-noise creates bubbles that destroy the evil dirt attacking your item! Says so in the instruction manual.

 

[raid]

Now if I knew how to use this Ultrasonic Cleaner, I would have taken care of many lenses here at home. Good for us at RFF to have you onboard, Brian. Next, you need to move to PC.

 

[Sonnar Brian]

Water, sometimes a little detergent, drop the part in, push the button. The Zizzy Sound does the rest.

 

[johannielscom]

Brian, those shots on ZIforum did the trick for me: just fixed an early 1952 J-3 that was off focusing. The rear helical had been disassembled and refitted one turn short. I noticed an approx. 0.6mm gap between the black parts with the rotation stop and the focusing mount. One more revolution/turn fixed it right into place and the lens now measures exactly to my known-good 1943 CZJ 50/1.5.

Thanks for providing these shots, they've helped me out many times now!

Tomorrow I'm finally gonna test drive the 'two-tone chrome' 1952 KMZ Jupiter-3!

 

[Sonnar Brian]

I'm glad to hear about the lens!


Please post the shots, along with fix-it notes, on the "Mad Scientist" forum.