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Disassembling zeiss Flektogon exakta mount
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PostPosted: Wed Dec 13, 2017 1:26 pm    Post subject: Disassembling zeiss Flektogon exakta mount Reply with quote

Hi everybody
I wish I disassemble a czj flektogon 35mm f2.8 exakta mount (see picture), the aperture ring and the focus are few bit stiff.
I searched info and examples on this site and on the web. The lens is this

I will try to describe step by step how to proceed, please if something is wrong don't you hesitate to correct me.

Last edited by gi0rgi0ba on Tue Dec 19, 2017 9:00 am; edited 2 times in total

PostPosted: Fri Dec 15, 2017 12:14 pm    Post subject: Reply with quote

I found the following articles https://www.google.it/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&cad=rja&uact=8&ved=0ahUKEwi_mJnn_ovYAhWIIOwKHZwFDC8QFggpMAA&url=http%3A%2F%2Ferebos.free.fr%2Fspip.php%3Farticle46&usg=AOvVaw2vNpIYJkkVixVO9oCU8OjB and http://rick_oleson.tripod.com/index-81.html
the type of lens described on this site is not the same, in any case I tried to unscrew the outermost retaining ring on the back just to separate the optical unit from the focusing unit. The retaining ring was so tight that I gave up to avoid breaking it. In this case this is not the correct way to proceed as you can see below.

Founding the optics scheme:

1) I proceeded removing the rear cover by unscrewing the four screws (red arrow on pic above), the pic below shows the diaphragm blade opening/closing arm

next steps
2) cleaning the lenses
unscrewing the ID ring you separate the front optics group. You can get the three glasses removing rings shown on pictures (see the green arrows, the middle one refer to the ring inside the structure).

the front glasses are these

the rear optics group can be separate from the barrel by acting on the inner ring (see the yellow arrow on the pic below)

first unscrew the blue arrows to separate the optics group from the blade structure and then the yellow to get the outer rear glass as shown in the image below

and the glasses are these

3) re-lubricating the focus mechanism:

the focus dial consists in three helical threads, we disasemble it in order to re-lubricate. The picture below shows the focus mechanism in all its parts

- first of all we have to make some marks in corrispondence of the leg which prevents the lens body to ratate. thus scratch marks for reference.

- second remove the leg and unscrew the inner thread where the optical unit sits
- third remove the inner screw
- last remove the middle thread, we need to know exactly how many turns we have made when separating it. This facilitate the reassempling process. I counted 5 turns.

At this point we have all the parts which we can clean accurately with naphta and then lubricate with some grease.
Follow the inverse process to reassamble it all. Screw the middle thread up to the marks (5 turns), fix it with the inner screw , then mount the inner thread and finally the leg.
Thats all.

PostPosted: Tue Aug 20, 2019 3:47 pm    Post subject: Reply with quote

Excellent tutorial - I've just bought one of these lenses but it needs a CLA.

PostPosted: Tue Jan 28, 2020 7:16 am    Post subject: Reply with quote

I like your article as always, thank you for sharing the experience.

PostPosted: Wed Jan 29, 2020 12:04 am    Post subject: Reply with quote

This is an excellent old thread and it's covering an Exacta mount Flektogon, but it might be worth mentioning this problem I had with an M42 Flektogon that had a very 'lumpy' and stiff focus. I took it apart, cleaned the old grease out and used a light multi purpose grease. The stiffness improved but it was still 'lumpy' in parts of the focus movement. I took it apart again, cleaned it, checked the helicoid for damage and found non, used a lighter grease, reassembled the lens and again the focus was lumpy. Took it apart again and tried the helicoid on its own - and it was perfect.

After some head scratching I traced the problem to a lever that ran in a V groove as the lens was focused. The lever pivot has to have some play, and although I didn't think it was excessive it was enough to allow the lever to tip very slightly as it slid along the V groove and the sharp corner would sometimes dig into the V groove and then bounce out again - which caused the lumpy focus.
I radiused the corners very slightly, reassembled the lens and it the focus was like silk.

The Flektogon 35 / 2.4 M42 mount

The lever - the unmachined finish of the forged lever can be seen clearly.

The V slot.

The area that was slightly radiused and smoothed. I didn't remove any material from the middle part to maintain any dimensional accuracy, I just smoothed it slightly.