auto takumar 35 2.3, infinity focus problem

[Aanything]

Hi all.
I'm new to this forum.
I have a problem with a lens i bought some days ago:
this is the lens

a beautiful auto takumar 35/2.3.

But, looks like I can't focus up to infinity.
I can get quite close to it at f22, but at wider apertures it looks like, when the focus is set to infinity, the lens is focusing somewhere between 8 and 9 meters far.
I tried hand-holding the lens in front of the camera without adapter, and, that way, it looks better (even if it's a little hard to tell): it's like it has some very small macro tubes attached.


I forgot to say that i'm using it mostly on a digital camera (a sony slt-a55v), and that i tried different adapters, and that those adapters work just fine with my other manual lenses.
I read somewhere that the front element of this lens, in some cases, can be unscrewed. May it have any connections with that?

If anyone has some suggestion, it would be greatly appreciated.

Thanks in advance.

A

[Rolf]