PHD2 Calibration

[starfield]

So I'm new to Autoguiding. I had a question on the general workflow when setting up PHD2. I typically need to setup everything from scratch each evening. Should I be running the Guiding Assistant at the start of each session? I imagine there's some variability that's introduced every time I set the scope up.

Thanks all for your advice.

[JayTee]

You are right. Because you set up from scratch every time you image you need to run the GA every time. You may not see a lot of change to your settings from night to night but your PA error will always be different (somewhat). Besides it only takes 2-3 minutes to do it.

Cheers,
JT

[Star Dad]

I don't generally do a recalibration (and 99% of the time I do a complete takedown of all my equipment). Of course, there are a couple of reasons. First off if there are clouds, forget about guiding. I just let the mount track as best it can... and I lose about 5-10% of my images due to wobble of the worm screw in the mount. Second, since I started using the Polemaster I find polar alignment to be as near as perfect as possible. If, during my first (1 minute test) exposure I see the ra/dec graph in PHD2 showing minimal corrections, I'm good to go and continue with imaging. If the ra/dec graph is showing wild oscillations then yes, I do a complete recalibration. That has only happened BEFORE I got the Polemaster. Like others on here, I am so glad I invested in the Polemaaster as it has saved not just time, but accuracy, and the physical strain (ie getting down on the wet cold ground) of looking through the polar scope.

[yobbo89]

for you, you should be calibrating evey setup because discrepancies with not getting the weight balance perfect, cone error and other small things,cables ectt. in general a fixed setup doesn't really need it.

[JayTee]

Just to clarify, are you asking about using the Guiding Assistant, or whether or not to do a recalibration?

Thanks,
JT

[starfield]

Actually both now that you mention it. I assumed I should be doing both unless guiding looked good out of gate.

[JayTee]

My mount has so many issues, I always do both. It gives me a sense of the health of not only my mount but also how good my PA is.

JT

[KathyNS]

Recalibration is only necessary if you are using ST-4 guiding instead of ASCOM pulse guiding, or if you changed your guide scope setup, particularly if the guide scope has been rotated relative to the imaging scope. If the guide camera mounts in the same orientation every time, and if you are using pulse guiding, then you can re-use the calibration from the previous session.

I haven't noticed the Guiding Assistant before. I'll have to check it out. Obviously, I can't advise you on it at this point.

[bladekeeper]

I set up from scratch each time. My scope comes out of its case, my guide scope comes out of its case, the cams come out of their case, etc.

I plug everything in, fire up NINA (what I use to capture with, software), which in turn pops up PHD2, which in turn automatically connects to mount and guidecam and begins looping. I have never recalibrated after initially doing so nor have I re-utilized Guiding Assistant.

My guiding is fairly consistent, though the better I balance the smoother the guiding is. I've even swapping imaging scopes (but used the same guide scope/cam combo). Smoother guiding with my ED80 versus my SV102T (less weight, shorter focal length).

I may try the Guiding Assistant again next time out. Might make things better. I suspect I'll see the same results. But, I don't know much. I haven't been guiding for an especially long time.

[starfield]

Thanks. Let me know your experience with the GA. I don't want to over obsess on the tracking graphs, but I am trying to learn my mount and figure out how to optimize my rig. (FYI running and EQ6-R Pro and Esprit 100). So far my adventures in autoguiding seem to be working, although the local LP limits me to 3 min subs so I haven't really pushed it.

[JayTee]

This is why I use the GA every time. Straight from the PHD2 manual:

The Guiding Assistant is an instructional tool to help you measure current seeing conditions and the general behavior of your mount and guiding subsystem. When it's run, it temporarily disables guiding output and measures the ensuing motion of the guide star. This can help you see the high-frequency motions caused by seeing (atmospheric) conditions. These cannot be corrected by conventional guiding because they occur at a much higher frequency than you can typically even measure. Trying to correct for them with conventional guiding is often called "chasing the seeing" and usually leads to poor results. Avoiding it is best accomplished by setting a minimum-move level that will cause PHD2 to ignore most of this high-frequency behavior. The Guiding Assistant can also show you other behavior of your system such as overall drift rates in right ascension and declination as well as peak-to-peak and maximum-rate-of-change measurements in right ascension,. While these things can usually be "guided out", measuring them can be helpful if you want to improve the underlying performance of the mount - for example, by improving your polar alignment if the declination drift rate is high. The Guiding Assistant can also measure the declination backlash in your system if you select that option in the user interface.

Can be found here:
https://openphdguiding.org/man-dev/Tool ... _Assistant

Cheers,
JT