Re: Fine tuning PHD2 settings for 1100 with Encoders #Guiding


Hi Andrew

I appreciate the struggle!

There are a lot of things to know and learn and understand how they relate to each other.

You may also get a lot of conflicting advice on how to go about understanding things, which can further confuse and complicate things. 

I do want to offer a few of my observations on some questions you have:

>>>>once I have an unguided PHD2 Graph, how can I determine my P-P arc seconds seeing

The guiding assistant output will show your P-P error, the DEC error is a rough approximation of your seeing conditions. 

>>>How can I determine what is the theoretical FWHM of my system?

assuming you aren't diffraction limited (and likely you aren't), you can take very short exposure of maybe 1-3 seconds. That should give you a good indication of achievable FWHM for your system and observing conditions. You should probably use a center crop to eliminate things like backfocus and collimation. 

>>>Once I know the P-P arc seconds seeing and my systems theoretical FWHM, how can I derive the best MinMo settings for a given imaging session? I thought all I needed was to get the Total RMS from the Guiding Assistant and the use this to determine my MinMo.

The guiding assistant's purpose is to provide you with that information and make that calculation. It's a really good starting point. However, there can be some artistry involved in tuning your system. For example, as I mentioned previously I noticed your min moves showed some oscillations in your guiding, To me this usually means you can tighten up the min move and probably improve your guiding results. That's from my couple years experience with the 1600ae in extremely good seeing conditions and making plenty of mistakes trying to figure out the same thing. 

Your encoders add an additional level of simplicity and complexity: they take care of a lot of things non-encoder mounts rely on guiding to do. For you (and me) that means you have to know the ideal balance between guiding and letting the encoders do their work.  The "bump guiding" Roland has referred to in the past is a good approach for this. 

Overall, if you are looking for a set of procedures to calculate conditions and performance, and then plug in these numbers that will somehow give you more accurate min move and improved guiding, I think you will find that an exercise in frustration.Calculating theoretical settings is a lot different than watching your guiding and knowing what to look for. The PHD guiding assistant is a great starting point, and I think experience will be the path forward for evaluating and improving things.

I'm sure others will have plenty of feedback on this as well.

On Mon, Oct 11, 2021 at 7:50 AM Andrew J <andjones132@...> wrote:
Hi Brian.

Thank you for taking the time to review the data and for providing guidance on how to upload my guide logs in the future. Once we get some clear skies here again, I will try and aquire the necessary data. As mentioned in another post, I am still struggling to get my head around some of these key concepts even thou I have been imaging since 2016. I have read and researched this on my own the best I can, but I obviously still don't get it. I am determined to get this figured out so I can get the most out of my AP mount (and maybe help others who struggle with this as well). I gues Push Hear Dummy is still not dumbed down enough for me... :)



Brian Valente

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