Tele Vivitar 85mm f1.8 t-mount preset won't reach infinity

[cheekygeek]

Just what it says on the tin. I have a Tele Vivitar 85mm f1.8 t-mount preset that had no mount. I ordered a t-mount for my Pentax K and it went on fine, but I can't reach infinity focus. Did I get the wrong kind of t-mount or what? What is the solution?

Thanks in advance for any insights.

[luisalegria]

Many possible reasons.

How much is it off infinity ? A lot or a bit ?

Two possible reasons for trouble that come to mind immediately.

Reason #1 I think is that not all T-mounts are the same. Some are slightly off a bit. I have had this situation before.
Check that the inner ring of the T mount is actually flush with the bearing surface that presses against the lens bottom.

Reason #2 The focus mechanism internal infinity stop may not be set correctly. This is not unusual either. Sometimes the only fix needed is to loosen a screw or two on the focus ring, shift it a bit and retighten to permit the thing to focus the last little bit. Sometimes the fix can be more complex, or not possible this way.

[parabellumfoto]