On my old Celestron it said to aim the centre point of the polar scope on an object far away, and to turn the telescope tube in declination (and in turn the polar scope) to get it so that the centre point stays steady on the distant object. Obviously, a bit of trial and error and iteration is required.
I did it once, it wasn't difficult.
Regards,
Renato
Yes Peter that is correct, the octane's etching does rotate, - as does the actual Octans stars rotate around the Celestrial Pole, so, you have to rotate the scope in RA (not declination as mentioned other post) Rotating in Dec will also rotate the polar scope and its etchings, hence, line up the etchings/ polar scope to match closely the position of the octanes stars - then adjust scope mount up/down - right/left if need and tweek in until happy - may need to rotate polar scope again to true it in more accurately
Hope this helps & all the best
Last edited by astronobob; 03-10-2014 at 09:01 PM.
Reason: add pic
Confused
If I screw the scope in to lock. The polar scope rotates with the mount in RA. Ok
But how do I now adjust the etching to align with Octans when the scope in in the start position? Or does that not matter as long as the etching lines up with Octans somewhere in the RA rotation. Since CSP is or should now be centre in any rotation?
Ok, no worries, No need to lock the scope for a polar allignment. You undo the RA Clutch (Im assuming you have an Equatorial mount) and rotate in RA untill the stars match the etchings, you can get an idea where the actual stars are by a star chart which matches the day/week/month your observing or imaging - or if you have 'Stellarium 'freeware prog' as shown in attached pics.. and Note where octans is today at this hour = 1st pic , , & where it is in 2 months time at this hour, ie 9:30'ish
Once have polar allighnment, then set scope up in park position, lock the clutches, turn mount on, set up time date, longitude Latititude etc, and do a star allignment
Thanks Bob. Got it now
Not really sure I needed a polar scope. I know the stars and can find them easily enough. I was having trouble getting the exact CSP position. I have been hovering around the right couple of stars. But that's through the telescope which I guess is not really polar aligning the mount.
Hopefully my sky is not LP enough to drown out the CSP through the small aperture of the polar scope.
Glad I could help Peter, Yeah, Octanes can be difficult to see in semi polluted skies, best then to try when theres no moon and prob a slight better chance after midnight when most house lights are turn off ...
if cant hunt them down - you can move to learning how to do a 'Drift Allighnment' which is another way to get a polar allignment - should be a few threads in this forum somewhere !
All the best
I don't know how old you are Peter, but if you are not a young man, I
wouldn't be surprised to see you take up drift aligning before long.
Assuming that your polar scope is illuminated, I hope that the brightness
is either variable, or not bright enough to swamp Octans and it's neighbours. Mine is useless because it has that problem, and is not variable.
raymo
No not illuminated. Just clear enough to see the octans etching.
50 next year. Drift aligning
Hmmm - that sounds like pretty tough going if the etchings aren't illuminated and you aren't somewhere really dark.
I'm forever switching the flashlight made to go into the illuminating unit on and off - on to see the etchings, and off to see the dratted little trapezium.
Personally, I have never gotten the little pattern into the field of view of the polar scope just by aiming.
Instead, I use the Vernier scale on my Dec axis and the bubble level on my tripod and make sure I have the correct latitude on my telescope.
Basically I line the telescope up roughly in the direction of the SCP. I check my bubble level shows the telescope is level. I set the Declination to that of Alpha Centauri. Then I move the RA axis and the base of the telescope around till I get Alpha Centauri first in the finder, and then in the eyepiece. Assuming your telescope is still level after that exercise, the pattern with be in the field of the polar scope. Then make the final adjustments.
Good luck - you'll need it. I always get a sore neck and knees after that exercise.
Regards,
Renato
The first night I had it set up I went straight to 2 minute exposures.
The for some reason I thought I'd revisit collimating again.
I checked again yesterday. The centre of the polar scope hardly moves off centre.
But the last 2 nights I've only managed 1 minute exposures. Why?
Over loaded mount? 2 cameras
Pointing west so going with motor instead of against?
At 2 minutes I'm getting enough elongation to drop back to 1 minute via trail and error.
Rechecked mount alignment and the octans stars are where they should be.
Good to write things down. I think I see my problem.
I balanced for one camera. 2nd piggy back? causing more noticeable backlash from RA motor/gear?
