Is there a way to tighten a collapsible lens?

[gregarpp]

I have been looking for an excellent sample of a 5cm2.0 lens.
I have found many with coating marks, now I got my hands on one that has no coating marks.

This lens like all the others that I have (now). When I turn the aperture ring, it will also turn the lens. It doesn't seem to take much to turn the lens.

The aperture's don't seem that stiff... just the lens barrel seems loose.

Is this easy to tighten up? I sent 2 of the lenses to DAG, better samples. But I have not gotten a response from him yet.

 

[John Shriver]

Presuming that the lens is a collapsible Summar, Summitar, or Summicron, there is no way that adjusting the aperture should rotate the lens, as they all have a friction lock on the bayonet of the collapsible mount. All of them are in non-rotating focusing mounts. Presuming you are giving them the proper 1/6 twist clockwise after extending them, if they aren't holding still, the friction tabs need to be adjusted.

Now, Elmar (35, 50, or 90) or Hektor (50 or 135) with rotating fronts, you just have to adjust the aperture first. No other hope.

 

[Ronald M]

The lube on the aperture has gotten sticky with time. Fix the lubracation problem if it does not turn freely. Do not start bending lugs as they will never be right again.

 

[payasam]

John, what can the lens be if not one of the three you name? I'd agree with Ronald that dealing with the lubrication makes a lot of sense while messing with the tabs makes none or thereabouts.

 

[John Shriver]

Only other 50/2 collapsible in LTM I know of is the Canon Serenar. A rare and early Canon lens, rather promptly replaced by a 50/1.9.

Oh, maybe Nikon made their LTM 50/2 as a collapsible?

I do agree with Ronald that having the lube on the aperture ring fixed is the right solution. A Summar, Summitar, or Summicron with good glass is worth the investment in a full CLA.