EQMOD home position changed after adding pointing info ???

[Spaced Out]

Hi All

I am just setting up my newly built pier with EQMOD and Cartes du Ciel for the first time. Never done this before and I’m loving using EQMOD over the hand controller, however, I have a small problem. As I have synced my first few stars in CDC my EQMOD home position has changed slightly. I’m hoping this is just a settings issue somewhere ?

Perhaps as I have synced stuff I have slightly moved things so the EQMOD home position has also changed a little ? I could live with this if the GOTO pointing was more accurate after the syncing but it isn’t, it seems worse !

Here’s how things look at the moment.

Any suggestions please ? 

[wxsatuser]

I always found once the first star is centred and synched the following ones are always in the fov.
Not spot on but by the time 3 to 4 are done the gotos are pretty close on centre.

As far as I know the home position should not alter with synching but if you undo the clutches or knock
either axis and don't get them back dead on, the home position will change and you need to resynch stars.

[symmetal]

Under Alignment/Sync section change the User Interface from Append on Sync to Dialog Based. With Append on Sync you can end up with many Sync points close together which upsets the pointing model and gotos. Dialog Based will effectively replace an old sync point point close to your position with a new one. Also delete the alignment sync points from time to time to start afresh. (Buttons just above the User Interface selection)

I find after a while the home position does report itself at 89 degrees or so though its physical position doesn't seem to have changed. Deleting the alignment point data clears these errors. 

Alan

Edited August 28, 2019 by symmetal

[Spaced Out]

2 minutes ago, wxsatuser said:

I always found once the first star is centred and synched the following ones are always in the fov.
Not spot on but by the time 3 to 4 are done the gotos are pretty close on centre.

Thanks for this reply. Yep, on the night I synced everything was dead centre and I was dead chuffed. The following night I noticed that the home position had slightly changed and all goto's, whilst still in the FOV, were out on the edge.

I don't think I've knocked anything and I've not touched the clutches. I'm left scratching my head a bit ! Maybe I just need to clear the syncs and set it up again from scratch.

 

[Spaced Out]

2 hours ago, symmetal said:

Under Alignment/Sync section change the User Interface from Append on Sync to Dialog Based. With Append on Sync you can end up with many Sync points close together which upsets the pointing model and gotos. Dialog Based will effectively replace an old sync point point close to your position with a new one. Also delete the alignment sync points from time to time to start afresh. (Buttons just above the User Interface selection)

I find after a while the home position does report itself at 89 degrees or so though its physical position doesn't seem to have changed. Deleting the alignment point data clears these errors. 

Alan

Thanks for this too. I'll try changing that setting and re syncing things to see if it helps.

In terms of home position reporting I've gone from 90 degrees to 89 degrees on my first night ! So if I delete my syncs should that go back to 90 degrees ?

[Spaced Out]

OK Update !

I cleared my sync data tonight and started again using Dialog Based setting but I have exactly the same problem. I started at 90 degrees home position but when I come to park after syncing it is saying 89 degrees something. I've synced on 10 stars tonight and the GOTO gets the target in the field of view but it is never centred, am I expecting too much ?

[symmetal]

I wouldn't worry too much that it doesn't read 90 when you park after gotos and syncing. When you use goto to go from one position to another the scope may need to reverse direction in RA and/or DEC and so the mount movement may have to take up the backlash in some cases and not in others leading to the object not being centred each time. As long as it doesn't seem to get worse the more gotos you make as it did in your first post is what you want to achieve. It doesn't actually issue a sync in the home position as that's the worst place in the sky to sync on. The RA can be anything you like and it's still correct so is meaningless. The Dec should still be at 90 but due to the backlash errors encountered during the gotos this may not be the case. There are backlash adjustment settings you can make in Eqmod which may improve the centreing of objects but I've not tried using them. I use automatic centreing using platesolving so the backlash errors are automatically corrected.

Alan