Vic - sorry to be so long answering, don't have time to get on the internet very often...

My 135-600 was a bit loose around the mount at first. There are several small screws at the mount that needed tightening. Also there is a "thumbscrew" (?) that is supposed to be loosened to allow you to rotate from landscape to portrait, etc. Be sure this is good and tight before mounting the camera.

Feel free to PM me if you have more questions, but remember it may be a week or two before I check back here again. Hope you enjoy the lens, and will look forward to seeing your great photos posted here!

Hi Mole,

I bought a K mount Pentax 135-600 like the one in your review and having a hard time to mount it onto the camera. The screw mount always come out first. Do you mind to give me a pointer when you have a moment?

Thank you.

Vic