Quote:
Originally Posted by Moon
Paul
I hope you fix this soon.
Can you remind me what scope this is?
James
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The whole setup is VC200L with SXVF-H9 on Losmandy SBS with WO72 FD and DMK21 for guidescope. The DMK is held by a star diagonal (used to be meade 1.25" flip mirror. swapping it out to the star diagonal didn't make any difference). All sitting on the AP900. I swapped guide rings the other day. Rebalanced and checked all connections. Everything is snug with no snagging or slop that i can detect.
Quote:
Originally Posted by mithrandir
Paul,
H0ughy's cable theory is good.
Is there any correlation between the declination and tracking error? The closer to the pole, the worse the tracking?
With that theory, NGC3372 should be worst and the Messiers best. The RA balance or a cable pulling tight might be part of it which could mean if NGC5139 is bad, anything else being shot at a similar alt/az should be too.
On another couple of groups, the discussion seems to agree that as long as your polar align is good (not necessarily perfect), for high dec targets you can guide on just about any part of the sky within about 30 deg of there. With more available pixel movement the guider can be more stable.
Andrew
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It does seem to be worse the closer I get to the pole but not always. Generally though its when pointing east to south. Yet if you look at M4 its spot on and even omega doesn't look too bad. But NGC3621 (spiral from last night) is not that far away. Polar alignment is excellent with 2-3 min unguided through the VC.
Quote:
Originally Posted by Merlin66
Paul,
can you check for me...
If I use CdC to monitor the direction of movement it seems to be in elevation?
(Would need more precise time etc)
If this is the case then it could infer than gravity plays a part - something sagging?
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No nothing snagging in the cables at all. I've checked and triple checked that.
I can shoot almost anywhere in the sky and it seems to work fine, with the exception of E to S. The direction of the drift always seems to be down and left which corresponds to moving the mount W and S (well they are the buttons I push to get same movement). And there doesn't seem to be much variation in direction or slope of drift.
Quote:
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Originally Posted by h0ughy
to me it looks like it is binding on an axis then releasing, or its pushing too much in one way like the calibration is out. move your cables away from electrical interference or sit in the lotus position and meditate on the fact that you are not the only one. it occasionally does it with me - and some times it just has a massive leap like the tectonic plates releasing a heap of energy.
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I'm really sure its not cables Dave, and I'm confident in the balance. But for you I'll check them again
Initially I started using phd last night and then swapped over to Maxim. The initial movement was huge in the subs and then seemed to settle down. I guess its time to start changing stuff around. Put just the VC on with a self guide SBIG. If that works try over and under with the WO and DMK. I can hear Gary screaming in the background OAG, OAG, ....but I don't have one atm so I'll just have to use what I have.
Thanks for the help guys. Fingers crossed for a clear night so I can keep on trying