Home
SearchSearch MemberlistMemberlist RegisterRegister ProfileProfile Log in to check your private messagesLog in to check your private messages Log inLog in

CZJ Biotar infinity focus problem
View previous topic :: View next topic  


PostPosted: Wed Sep 19, 2018 6:19 am    Post subject: CZJ Biotar infinity focus problem Reply with quote

Hello everyone

This is my first post as a member, after reading so many topics in this forum. Hope you guys can help me.

I have a Zeiss Biotar 58mm f2, silver 17-blade version with red T (SN 3112123). Formerly, it had an Exakta mount but it was replaced with a M42 screw mount. I bought it for really cheap and it was really dirty and quite frozen, due to the hardened grease inside its helicoid. It took a lot of force to make the focus and aperture rings to rotate. A friend of mine and I took the lens apart and cleaned it, removing the old grease and dirt from it, making the aperture and focus rings softer to move.

The problem I'm having is with the focus distances. This lens usually focuses from 0,9m to infinity, but mine only focuses to about 2m when the focus ring is set to infinity. I thought that it was still useful for some portraits, but the lens felt even more limited to use when I tested it, both in digital and in film. Since then, I didn't dare to disassemble the lens again, afraid of making it worse.

Hope you guys can help me with this. Thank you all.


PostPosted: Wed Sep 19, 2018 3:14 pm    Post subject: Reply with quote

Welcome jhayashileite

Intuition says the focus helical was not started on the correct thread; helicals are not a single thread but have multiple starting points. You may need to try each before finding correct thread which allows infinity focus.


PostPosted: Wed Sep 19, 2018 3:59 pm    Post subject: Reply with quote

Unfortunately it will have to be taken apart. You did not assemble it correctly - a typical rookie mistake, helicoid was not started at the right point.


PostPosted: Wed Sep 19, 2018 4:27 pm    Post subject: Reply with quote

Hi,

You may find this thread helpful if your lens is similar.


http://forum.mflenses.com/stiff-focusing-ring-on-a-biotar-58-2-no-problem-t24157.html


PostPosted: Wed Sep 19, 2018 5:43 pm    Post subject: Reply with quote

Thanks a lot for the replies, guys. I will work on it as soon as I can. Have a nice week.


PostPosted: Sat Sep 22, 2018 11:56 pm    Post subject: Reply with quote

Quick update:

I was able to disassemble the lens and bring back infinity focus, but my problem now is screwing the rings back together. The screws that I still have on the lens are almost unusable, being old and worn off, specially after my attempts to fix the lens.
I would like to know if there are any ways to replace those screws or other way to but the rings back in place. It already works properly, but my Biotar has some inside threads exposed to dust (and is looking like an Industar 61).

Any help will surely be appreciated.