[MickeyJay]

With my Pentax PF80 ED and a CP990 I could not
stop the equipment from moving front
to back.

When I sighted in I had to aim slightly below
the subject because the weight of the camera
would cause the front of the scope to go higher.
Even doing that was no guarantee that when I
touched the shutter button the scope would stay
on target. In most cases it did not.

By placing a bunji cord over the top of the scope
at its mid-point and then attaching the
ends of the cord to the braces that are attached
to the legs and the center piece of the tripod
pulls the scope down tight to the tripod....problem
solved. Oh happy days.

Mickey

In order to see birds it is necessary to become
part of the silence. (To this I would add: have
a bunji cord.)

[Andy Bright]

Hi Mickey,
Yes, this used to be a common problem. The normal way around this was to incorperate a sliding plate that altered the centre of balance of the set-up. A good head should also cure it, and one with a built-in sliding plate is even better.
It's less of a problem these days as scopes and the cameras are getting lighter all the time, the cp990 is quite a heavy beast compared to newer cameras.
Glad you managed a cheap work-a-round.
Regards,
Andy