PHD2 - better tuning
Astro Photos2
bw_msgboard
Hi Astro. I think there’s plenty of room for improvement here, probably by 50%. To start, you should follow these instructions and configure EQMOD for better guiding:
https://github.com/OpenPHDGuiding/phd2/wiki/EQASCOM-Settings
Your current guide speeds of 0.1x sidereal are far too slow for responsive guiding. After you’ve done that, you can follow this procedure to get a baseline measurement of your mount’s capabilities:
The question is not how to tweak PHD2 settings, it’s how to understand the limitations of your mount, what can be done to improve it, and then what is the best guiding strategy for mitigating whatever problems remain. You should anticipate having some Dec backlash problems and a high level of uncorrected periodic error in RA. These are points you should research and come up to speed on. Also, you’re using one of these wheezy finder-scope arrangements for guiding, so that will be a constant source of weakness. Those arrangements usually won’t stay tight so they often cause large excursions in the guide star and overall poor results.
You will have to decide how much effort you want to put into this relative to how serious you are about your final images. Your current total guiding RMS is over 2.0 and it would be a reasonable goal for this class of mount to get that down to 1.0 assuming your local site conditions will support that.
Good luck,
Bruce
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Astro Photos2
Astro Photos2
bw_msgboard
Yes, the overall guiding has improved, no question. You cheated a bit by running the 21:34 sequence at Dec = 47 – that masks the full extent of the uncorrected periodic error in RA. Doing measurements and testing close to Dec = 0 is a better approach. Your Dec guiding now is quite good, the PHD2 Dec backlash compensation seems to be effective. But your challenge now is to avoid getting elongated stars when the RA performance is nearly 2x worse than Dec. You should probably come up to speed on periodic error correction and how best to get that done on your mount – other mount-specific forums will have lots of discussion on that. You can see you have nearly a +/- 15 arc-sec periodic error, most of which is occurring at the native worm period:
To view this discussion on the web visit https://groups.google.com/d/msgid/open-phd-guiding/edf57304-7103-4348-b537-55dab8a1ccf6n%40googlegroups.com.