Zeiss Biometar 80mm 2.8

[santino]

Hi!

For about one year I'm the owner of a Zeiss Jena Biometar 80mm 2.8 with Pentacon Six mount. The lens performs fine and isn't much worse than my CF Planar but theres a problem, focusing is very hard (you have to use much power to move the focusing ring). So as I repaired some lenses in the past by dissambling them, cleaning etc. I did the same with that lens but... the problem is still there. The helicals inside are very hard to match, only two turns and the optical block is mounted. Now here's my question, what could be the reason for causing the lens to work hard? it is absolutely clean and relubed.

thanks

 

[Rob]

I've come across this with a lens that had been dropped - the barrel had distorted in a minute way and the lens no longer moved without extreme force rotating the barrel. I never actually fixed it though, so this is probably of no help at all!

Rob

 

[Hertz van Rental]

I was going to say the same thing.
Lenses, like cameras, are precision instruments. Doesn't take much to put things out slightly - 0.01mm can be enough: the thickness of a cigarette paper. A small knock in the wrong place can be enough. Putting it right - if not impossible - will probably cost more than the lens is worth. To start with you'd need to find where the distortion was and how much it was distorted by before you could think about how to fix it. I suspect a camera repair shop would tell you pretty much the same.
It would be cheaper to go to the gymn and exercise to build up the muscles in your focussing arm.