Re: Multi star guiding with PHD2 #EXOS2 #astrophotography #CloudyNights

Wes Mcdonald

Dave and Walter

New multi star PhD will indeed allow faster guiding cadence, and I also have found the mount best at higher cadence.

1.17 does not address what you are seeing Dave.  At the moment we don’t see how firmware at 1.16 or higher can cause this.

Please post on the beta site some logs from the driver during this issue.  The last files were empty.  


On Tue, Mar 30, 2021 at 5:15 PM Dave Cherry <andromedacity@...> wrote:

Hi Wes, good timing


I’m doing the Crab at the moment

Still having issues unguided

Still doing the shift left shift right thing.

On 1.6 at the mo,  would there be any improvement on 1.7?


Here I’m using 100% RA aggressive on a 0.5 sec multi-star guide!  to keep it usable...


Dave C







Sent from Mail for Windows 10


From: Walter Vinci
Sent: 30 March 2021 21:58
Subject: [ESPMC-Eight] Multi star guiding with PHD2 #EXOS2 #astrophotography #CloudyNights


Hi All,

You might be already aware of this, but latest PHD2 build enables multi star guiding. There is a long thread on cloudy nights
I just wanted to mention it here since I believe it is especially relevant for weight-capable but entry level mounts like the exos2. my experience so far with my exos2 is that it needs to be guided aggressively. I typically have best rms with guiding exposures of 1s, despite picking up a lot of seeing fluctuations. Multi star guiding should allow for a more accurate guiding with very short exposures by averaging out a lot of seeing (three times  smaller rms due to seeing with nine guiding stars). Hopefully this new functionality allows to push further the limits of the exos2 for astrophotography.

I will try it this week. Let me know how it works for you,



Walter Vinci

Starfield 0.8 Field Flattener/Reducer.
ZWO ASI290mm-mini & Orion 50mm Guide Scope
Canon EOS Rebel SL1
SharpCap, APT, PHD2, SiriL, Stellarium


Scopes: Sky Watcher 200PDS, Skywatcher 72ED
Mount: Explore Scientific PMC8 EXO2
Cameras: ASI 294MCPRO Coooled, Altair guide cam + 50mm scope
Software: Sharpcap Pro ,PH2, Stelarium Startools

Wes, Southport NC
EXos2-GT PMC-8, iExos 100
ES ED 127, 10" LX200GPS+wedge, Astro-Tech 8" Newt, ETX-90, 60mm no-name guide scope ~ 260mm FL
Polemaster, Orion ST-80 and SAG, ZWO 290MM, D5300 astro modified
Nina, Bootcamped Mac Mini control computer, RDP to iMAC
110 amp hour lead acid deep discharge battery for field power
Electrical Engineer, Retired

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