SharpCap Forums

Is it possible you didn't leave enough time for a new frame and solve after making an adjustment?

Hello Culvenion, thank you for your reply.
Yes, I was patient to wait for the image to be solved each time.
The alignment would change as I just watched, the numbers and quality changed without any inputs from me.
It is a "puzzlement".

Fivelpolar

One good technique to try to work out what is going on is to gently push against the mount (or tripod). Unless you have something like a Paramount then a steady but gentle push will be picked up by the polar alignment routine.

Why do this? You get to see a few things like

* How quickly does it respond - gives you an idea of how long you need to wait after adjustments
* Does it go pretty much back to the old value when you stop pushing? If not then something may be slipping/shifting rather than being firm

Applying pressure in different areas (tripod/mount/scope/guide scope) can help reveal any problems with the rigidity of the setup, which is the most likely cause for what you have seen (but it's difficult to be specific as to *what*)

hope this helps,

Robin

Hi again Robin. Prior the last run through I had accidentally bumped the CW or the guide scope.
After that I started the routine from scratch. The last time through I did not bump anything, but the results still changed on their own. I finally got a fairly stable "Excellent" and locked the AZ and EL clutches. After 30 second it dropped to "Good", but I quit at that point. I will verify the polar alignment soon using thee PHD2 drift routine.
If all goes well it won't show the need for further adjustment.

Fivelpolar

What's your setup? A tripod on soft ground can easily cause this sort of thing if it is settling slightly.

cheers,

Robin

Robin here is my setup:
1. Mountain Instruments MI-250 mount
2. Mounted on a metal pier-sand filled/concrete base in my observatory (split roll-off roof)
3. Zwo asi 185MC cmos camera on a 50mm mini guide scope (quite stable)
4. Mounted on my Meade LX 200 8" OTA
5. The latest version of Sharpcap Pro (just updated prior to the polar alignment)
Focus as good, although Polaris was a lot larger than the nearby stars.
Gain=380-400, Brightness appx. 20, Gamma=30
exposure=1-2 seconds
Frame rate= 2-8 per second depending on solved or not solved
Digital Gain Max, Noise reduction=5. Seeing conditions clear to thin clouds, light breezes, was dark but moon rose near the end of my trials.

On my mount I've discovered that when I turn the azimuth locking screw that the rating sometimes downgrades from Excellent to Good. I've learned to rotate a little right of the zero-point before locking down because the screw introduces a bit of "left". When satisfied I then "man-handle" the mount a little bit to simulate the stresses it will undergo during use. Sometimes I will lose my Excellent rating after doing this. Rinse and repeat until satisfied.

Hi oopfan and thank you for your suggestions.
My mount has two locking knobs for each of AZ and EL.
What I finally tried was to partially tighten them and then do the last adjustments.
I think that helped a bit. When I check the result with PHD2 Polar drift align I will know if there is still an issue.
There is always a challenge to overcome in this hobby.

Fivelpolar

Yes, yes, that is exactly what I do: partial tightening when getting close!

An update to all on the PA routine.
I checked the results, and the very small amount of DEC drift will be easily guided out.
I also re-did the PA routine, and the results are repeatable.
Now on to PEC training, and I can then do some DSO imaging.
Thanks to all for your help.

Fivelpolar