Another newbie question on alignment


Parag Modi
 

Hello,

I have a question on how the multi-point alignment transformation is stored.  My setup includes iEXOS-100, POTH hub with ES driver selected and APT.  I'm using just a plain Nikon D7200 with a Sigma 18-300mm lens and no guiding.  I found a cool script in APT that automates a four point alignment.  Basically it moves my camera to four equal points in AZ/ALT, does a platesolve and sync.  I tried that the other night and it seemed to have worked good since my subsequent GoTo moves were pretty close.  My questions are:
1) Where is the alignment information stored and used?  iEXOS firmware?  POTH hub? or APT?
2) Is there a way to view and save this alignment information in between the sessions (over days) if my mount hasn't moved?

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Parag Modi

Mounts: ES iEXOS-100
Scopes: APS-C Sigma 18-300 mm
Cameras:  Nikon D7200 (Unmodified)
Misc: Bahtinov Mask, K&F Concept Clear night filter
Software: ExploreStars, Stellarium, APT


Wes Mcdonald
 

Parag:

There is no storage of alignment information when using ASCOM, as the driver does not modify pointing based on any model.  When you do a plate solve, the exact position of the field of view is determined.  Using this information an application such as APT (NINA does this also, as would any other app) can determine the error in poiniting.  It then moves the mount the required amount to achieve the actual desired pointing position.  By syncing the mount while at the correct poiniting position the mount immediately knows its correct celestial location relative to its motor counts.  If the mount is pretty well polar aligned this is all it needs to make good goto moves thereafter.   If the mount polar alignment is not good, the gotos will become worse as you move the mount further away from the place where the sync was performed.  However if you do a plate solve at the new location the desired target will soon be centered.

Congratulations!  Plate solving is one of those magic bullets that makes life good!  Add auto focus and you will wonder what all the fuss about astrop[hotography was ever about!

Wes.


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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


Parag Modi
 

Wes,

Thank you.  So basically there is no benefit to be gained with multi-point alignment when using ASCOM.  I'm just better of simply using plate solving to get to my targets.

I agree, Plate Solving has simplified things a whole bunch.

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Parag Modi

Mounts: ES iEXOS-100
Scopes: APS-C Sigma 18-300 mm
Cameras:  Nikon D7200 (Unmodified)
Misc: Bahtinov Mask, K&F Concept Clear night filter
Software: ExploreStars, Stellarium, APT


Wes Mcdonald
 

Parag:

Well, I am not sure there is no benefit, but the benefit is not with the driver.  I guess it could be possible for the application, such as APT, to somehow use this for its own purposes, in the same way explorestars does.  But I kinda doubt it.

NINA just does a platesolve and moves and it works like a charm.  So plate solve is the answer.

Wes.


--
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