Biotar with loose front element

[ricklb55]

I recently acquired a C.Z.J. Biotar 58mm f2 lens with an Exakta mount for $75, a very good deal. However, the front most element on the lens is just a tad loose. Its the part of the lens that contains the aperture adjustment ring. See attached picture. The lens works fine, the apertures look good and it focuses properly. Beyond the annoyance of the rattle, is this looseness anything to be concerned about? Thanks.

[newst]

It's hard to tell from the photo angle but that looks like a preset lens. If so it seems that the preset ring is a little loose. Nothing to worry about at all.

[luisalegria]

Its a semi-auto lens.

The typical "arm" on Exakta lenses came in with this thing - this is the first lens with an "arm" I think.

You cock it before taking, focus wide open, and when you press the shutter button on the lens the spring stops down the aperture. Otherwise if you don't cock it its not auto at all and works like, IIRC, a pure manual aperture (maybe preset).

Several other makers introduced similar mechanisms, Zeiss for Contax with the first pin, copied by Edixa, Asahi/Pentax, etc. Quite a few had semi-auto lenses for a while.

Later auto lenses didn't need cocking.

I have one of these semi-auto Biotars in pieces I was trying to repair, I should dig it up.