Re: #iexos-100 - issues with PDH2 guiding #iEXOS-100 #TECHNICAL

Wes Mcdonald


A few things you can do:

I see your calibration distance is set to 25 pix.  That is the setting Bob is talking about.  Move that that up to 50.  It is set in calibration/advanced in PHD.

I also see you were trying to cal at 30 deg Dec.  I believe you want to be closer to 0 Dec.  But in truth I don't think that is the major problem.  Also I usually try to calibrate closer to the meridian.  Suggest you try something like azimuth at 150 degrees. 

Make sure your guide camera is oriented along the horizon when your mount is in polar home. Ensure it is tight in the finder scope.  I think that has messed me up in the past

During the day time set up your mount and point it at a tree top or tower or something far enough away that you can focus the scope.  Put your camera in live view.  Set your guide rate in the ascom driver to 1. Now with the mount running, use PhD manual guiding buttons to see if you can manually guide in RA.  Since your rate is set to1, you can stop.the mount from.moving in RA by guiding continuously manually toward the east (I think).  You will see the image in the live view change as you guide vs not guide.  When you see movement in the correct direction you can stop guiding.  In RA the moment you stop guiding the mount will resume moving in RA in the opposite direction. Unless there is a great deal of backlash.  If there is you can count how many seconds it takes to resume.movement.  that number of seconds x 15 is your approximate backlash in arc seconds.

Read about the star cross test in the PHD manual.  Perform that test at night.  The shape of the cross will tell you about backlash.  If things are working, the cross image will be good.


Wes, Southport NC
PMC-8, ES ED 127, 10" LX200GPS, Astro-Tech 8" Newt, ETX-90
Polemaster, Orion ST-80 and SAG
Electrical Engineer, Retired

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