Anyone out there with experience in using a helical focus . I have just brought a Chinese guide scope which has a helical focus mechanism. It is smooth but I have noticed that the draw tube is wobbly until you tighten up the lock thumb screw. Is this typical of this type of focus mechanism.
When there isn't anything in it, it seems well made. But the moment you put the QHY5L-II into it it is obvious that you can wobble it up and down even I know that's not going to be good in a guide scope
Any comments.