I've been getting to grips with modelling for PA and collimation, but fear it's giving me the run-around. I haven't got as far a building a whole sky model yet. The following is copied from a conversation with Mike Paling and slightly edited.
What I've been doing is turning the motors on and letting Autofind tune the motors (Only getting 64% ATM, I did have 75% until I made some changes and rebalanced) before doing a Homefind, then slewing to the Park1 (Zenith) position and refining it with a spirit level before synching. In Cartes du Ciel I select a star (ATM either Vega or Deneb), and start capturing images, using the "continuous" setting in Maxim DL's camera control. When I have the star centred in Maxim's crosshairs I click "synch" in CduC. This will be my first alignment star. I then do a new Homefind Position.
This is now where things get "wobbly".
I click on Start Pointing File, whereupon a get a warning telling me to re-synch the mount else I'll get large offsets. I thought I *had* synched it. OK, select the same star from the Objects icon, slew (Still on crosshairs) and click the synch icon. Try again, same message. Oh well, start anyway.
Use the star I'm on as No1, click the target with the tick in it to say it's centred, then on to No2, go near meridian and fairly south, repeat, star No3 is to the east and on the equator (-ish), then No4 fairly high but not to near the pole (I tend to use alpha Cassiopeia ATM). Click Stop pointing file, and calculate the result.
Chances are I'll see crazy offsets measured in *hundreds* of arc minutes for all the parameters (Once I saw the PA offset measuring 1000 minutes!), even though each star was landing close to the centre of the frame.
Clear that model and start again, also looking at the bottom of the Autoslew window where it reports the alignment offset for each star.
This time I get sensible offsets (Even though I get the same warning about re-synching), so proceed to the PA tool, find star in the specified area and do the PA.
So far, so good, however....
I've not done a full model yet, as when I've tried going across the meridian I get the crazy offsets again (Even though the target star is still hitting near the crosshairs), so something else to sort out. I tried to use Autogrid in Sequence but got a fatal error (See the thread about it).
So.... can anyone throw some light on what I'm missing out, or doing wrong? I've got the PA error down to no more than 1.5' on each axis, and the collimation down from 126 (126 what? Minutes?) to about 12.5
Edited by DaveS, 11 September 2016 - 12:25 PM.