Hi Robin,
Quick review of setup: 8”SCT hdedge, native f/10, PHD2, asi2600MC, latest SC version
I reviewed main log and noted the live stack log or any details pertaining to it, are not included. I also noted I can’t retrieve prior night’s live stack log. I’ll try and describe what’s happening, and based upon that and your experience, maybe you know of a “fix” for this issue. If not, next time out I’ll try and save screenshots of live stack log.
Here are examples of the alignment stat’s results, x & y, by frame, 5 min subs:
First 1-3 frames 1-3, -1-3 very little variance
4th -49, -45 Large one frame var
5th -49, -47 Little change
6th -102, -52 Large one frame var
Sometimes it stretches out to 8-9 frames, but eventually once variance hits around 100, either axis, I begin to lose 5-10% of the total frame, once stacked. It’s at this point I usually close down and restart live stack anew. Later in post processing, I’ll decide whether to exclude the specific outlier frame and its impact on total image.
Why do the results change so quickly and dramatically with one frame? If it was a PA issue, I would expect the results to creep rather than to materially change in one frame?
Any advice?
Regards,
John
Alignment Status Issues
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Re: Alignment Status Issues
Hi John,
what mount are you using? Is it well balanced and are the clutches tight? It sounds like something mechanical might be slipping intermittently from the description of big movements now and then rather than a steady drift.
If you have SharpCap set up to save the raw frames when live stacking, I'd expect you to have either badly trailed or 'double vision' images in some of the frames where the shift occurred. The double vision effect (all the stars twice) would happen if the shift was relatively quick in the middle of a frame.
Another thing to think about given that it is an SCT is the possibility of the mirror shifting as the orientation the tube changes. I seem to recall that Meade SCTs had the worst reputation for mirror shift and that Celestron were better, but still a possibility.
If you have a guide scope and camera available then you could pop that onto the side of the SCT and have PHD2 monitor the tracking (even if it isn't really guiding). If the mount is glitching then PHD should pick it up as the guide star will jump. If the PHD2 trace looks good but you are still seeing the problems then mirror shift or the camera shifting might be more likely.
cheers,
Robin
what mount are you using? Is it well balanced and are the clutches tight? It sounds like something mechanical might be slipping intermittently from the description of big movements now and then rather than a steady drift.
If you have SharpCap set up to save the raw frames when live stacking, I'd expect you to have either badly trailed or 'double vision' images in some of the frames where the shift occurred. The double vision effect (all the stars twice) would happen if the shift was relatively quick in the middle of a frame.
Another thing to think about given that it is an SCT is the possibility of the mirror shifting as the orientation the tube changes. I seem to recall that Meade SCTs had the worst reputation for mirror shift and that Celestron were better, but still a possibility.
If you have a guide scope and camera available then you could pop that onto the side of the SCT and have PHD2 monitor the tracking (even if it isn't really guiding). If the mount is glitching then PHD should pick it up as the guide star will jump. If the PHD2 trace looks good but you are still seeing the problems then mirror shift or the camera shifting might be more likely.
cheers,
Robin