qestion on RA and DEC Balancing

New to Astronomy. Have Celestron C-150 HD. GEM Mount. I first balance scope
in RA and then in DEC. Would like to know if there should be any type of
"drift" when the RA and DEC are unlocked if they are properly balanced? I
believe they are balanced but when I point on a celestial object I have to
immediately lock the RA and DEC to eliminate this "drift". By drift I mean
the scope will move slowly but it is not real slowly trying to capture it in
the field of view of the scope. This normal? Or do I have to really fine
tune the scope to eliminate this? Seems if I stop at an object that scope
should not move at all but having a hard time tweaking it.
Thank You

n3drk wrote:
New to Astronomy. Have Celestron C-150 HD. GEM Mount. I first balance scope
in RA and then in DEC. Would like to know if there should be any type of
"drift" when the RA and DEC are unlocked if they are properly balanced?

Theoretically, no, but it is useful to have the RA axis very slightly
unbalanced so that it is being driven against the unbalance in order to
reduce any backlash/slack in the system.


I
believe they are balanced but when I point on a celestial object I have to
immediately lock the RA and DEC to eliminate this "drift". By drift I mean
the scope will move slowly but it is not real slowly trying to capture it in
the field of view of the scope. This normal? Or do I have to really fine
tune the scope to eliminate this?

If I understand you correctly, you do have some unbalance in the system.
This is almost inevitable because, for example, different eyepieces have
different weights. The simplest solution is to slew the telescope as
close as you can with the finder, lock the RA and Dec (keeping the
object in view), then use the drives/slo-mos to centre the target object
in the eyepiece of the main OTA.

Best,
Stephen

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"Stephen Tonkin" wrote in message
...
n3drk wrote:
New to Astronomy. Have Celestron C-150 HD. GEM Mount. I first balance
scope
in RA and then in DEC. Would like to know if there should be any type of
"drift" when the RA and DEC are unlocked if they are properly balanced?

Theoretically, no, but it is useful to have the RA axis very slightly
unbalanced so that it is being driven against the unbalance in order to
reduce any backlash/slack in the system.



Presumably this means that the imbalance needs to swing the scope ever so
slightly in the opposite direction to the RA drive direction ? In other
words move my counter weights a little further out. I'm too fuzzy headed
today to work out if the opposite is true in southern climates.

Regards,
Ed.

Ed Astle wrote:
In other words move my counter weights a little further out

Depends which side of the meridian you're observing on. Scope-heavy if
you're observing W (i.e. scope on E side of mount), cw-heavy if you're
observing E (scope on W side of mount). Or, put another way, whatever is
on the E side of the mount should have the greater moment. It's the same
in the S hemisphere.

Best,
Stephen

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+ + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + +

"Stephen Tonkin" wrote in message
...
Ed Astle wrote:
In other words move my counter weights a little further out

Depends which side of the meridian you're observing on. Scope-heavy if
you're observing W (i.e. scope on E side of mount), cw-heavy if you're
observing E (scope on W side of mount). Or, put another way, whatever is
on the E side of the mount should have the greater moment. It's the same
in the S hemisphere.

Best,
Stephen


Thanks very much. I think I understand why now - to get the gear faces to
always be mating instead of floating inbetween (ie in backlash land) ?

Regards,
Ed.