Dave Grennans new scope

And if so, is the scope software not good enough to provide accurate tracking to begin with?

As Jed mantioned, its nothing to do with the software, its a hardware issue. (Sounds like a line i'd use a lot at work) :lol:

Basically the mechanical gears which move the mount cannot be made precise enough to allow for perfect tracking over long periods of time. Unless the mechanics are very bad you would not see the errors while you use the scope visually, but as soon as you attach a camera the tracking errors become all too evident in all but very short exposures. More expensive mounts have less of this periodic error, but all mounts have some, no matter how expensive they are. Even tiny bits of grit or dirt ingressing into the mechanics will cause error like this. This is why you need to employ guiding to correct for the error and keep the tracking with a *very* tight tolerance. That tolerance generally should not exceed 2 arcseconds of error.

Thanks for that lads.
I understand now.