Alignmaster ALT-AZ adjustment problem

cplloyd42 (Paul Lloyd) · #1 20-01-2015, 05:38 PM

Hi,

I have recently started using AlignMaster to improve my equatorial mount's alignment. The software is a real boon and is easy to use, but I have one major issue:

When I select either AZ or ALT to correct the mount's misalignment, the software moves the target star in two directions, instead of just one. I can't see how the software is doing this (it should be just one direction). Of course, with the star now off-set in the other direction to the adjustment, it's not possible to centre the star, and I'm left scratching my head as to where to move the star to.

Would anyone know how to get Alignmaster to move the star in just one direction at a time? Alternatively, does anyone know of a workaround that works effectively? My mount is a Losmandy G11 with Level 4 Gemini controller.

Thanks in advance,
Paul.

Peter.M · #2 20-01-2015, 07:01 PM

This would happen if the mount is not properly leveled, or if the alignment is a fair way off. What I usually do, is when you tell it to adjust the azimuth and it slews away from the center, you move the bolts to get the star so that a line running perpendicular the the motion of the star would go through the center. This will be the closest you can get the star to the center. Then you do the altitude in much the same way, except bringing the star to where it was left after the azimuth adjustment.

Your next iteration should make it possible to get it closer to the center.

Nortilus (Josh) · #3 21-01-2015, 10:22 AM

i use it too as it is quick and easy and you can get really close to perfectly aligned. if you use a camera/webcam to centre stars then when you do your first adjustments just get it as close to centre as you can. it will eventually come to centre the closer you get to alignment...

cplloyd42 (Paul Lloyd) · #4 21-01-2015, 01:35 PM

Thanks for your input, Peter - that was quick work.

I'm pretty sure that my mount is levelled. Before putting the mount on the tripod I check the level of the top of the tripod with a spirit level, switching it through 180-deg to ensure there are no errors in the spirit level. I do this in 3 places, once over each leg of the tripod. Also, I find that I'm pretty close to alignment when I start Alignmaster as the target stars are within the field of a 35X reticle eyepiece, and Alignmaster reports that both axes are <15 arcmin out.

I have tried your method of "centring" the star in the correction phase, this seeming to be the logical way of doing it. On my first occasion I did get steady reduction in the errors. However, on my second occasion I ended up just cycling around the initial error, with first one axis reducing while the other increased, and the next iteration swapping the axes around. That's why I decided to post this query to see it anyone found a reliable method. This last time I gave up after 4 iterations, and the result was a slow drift - too much for 5min exposures. Perhaps I need to use the program more to get some experience with it.

I noticed that someone suggested unticking the "Correct axes separately" option on Alignmaster's startup screen, allowing you to alter both axes at the same time to bring the target star into the true centre. Unfortunately, there was no follow up on this comment as the original query poster found an alternative in his HEQ handbox software. Has anyone tried this, and if so, what success did you have? I will try it - I can always go back to the method you suggested, Peter, if it doesn't work. All I have to do is wait for a clear night!

Clear skies,
Paul.

cplloyd42 (Paul Lloyd) · #5 21-01-2015, 01:44 PM

Quote:

Originally Posted by Nortilus

i use it too as it is quick and easy and you can get really close to perfectly aligned. if you use a camera/webcam to centre stars then when you do your first adjustments just get it as close to centre as you can. it will eventually come to centre the closer you get to alignment...

Nortilus - that's the theory, but my most recent experience was one where I couldn't diminish the alignment errors. I put this down to the fact that the shift in both axes during the correction phase of Alignmaster made it difficult for me to decide when I had applied the correct amount of adjustment of both ALT and AZ. (See my last reply to Peter.M.)

Paul.

Peter.M · #6 21-01-2015, 04:29 PM

Quote:

Originally Posted by cplloyd42

Thanks for your input, Peter - that was quick work.

I'm pretty sure that my mount is levelled. Before putting the mount on the tripod I check the level of the top of the tripod with a spirit level, switching it through 180-deg to ensure there are no errors in the spirit level. I do this in 3 places, once over each leg of the tripod. Also, I find that I'm pretty close to alignment when I start Alignmaster as the target stars are within the field of a 35X reticle eyepiece, and Alignmaster reports that both axes are <15 arcmin out.

I have tried your method of "centring" the star in the correction phase, this seeming to be the logical way of doing it. On my first occasion I did get steady reduction in the errors. However, on my second occasion I ended up just cycling around the initial error, with first one axis reducing while the other increased, and the next iteration swapping the axes around. That's why I decided to post this query to see it anyone found a reliable method. This last time I gave up after 4 iterations, and the result was a slow drift - too much for 5min exposures. Perhaps I need to use the program more to get some experience with it.

I noticed that someone suggested unticking the "Correct axes separately" option on Alignmaster's startup screen, allowing you to alter both axes at the same time to bring the target star into the true centre. Unfortunately, there was no follow up on this comment as the original query poster found an alternative in his HEQ handbox software. Has anyone tried this, and if so, what success did you have? I will try it - I can always go back to the method you suggested, Peter, if it doesn't work. All I have to do is wait for a clear night!

Clear skies,
Paul.

Ok, if your errors are not getting better there is a few things you can check. I have correct axes seperately ticked so that should be left alone. The thing that is probably happening now is in EQmod, there can be no sync points when you start, and if you have it set to "append on sync" alignmaster will add sync points to the model. You do not want this to happen, so in EQmod, set it to "dialog based" and click to clear any saved points it has.

cplloyd42 (Paul Lloyd) · #7 22-01-2015, 09:25 AM

Peter.M

I think you misread my last paragraph - I was commenting that SOMEONE had this problem with an HEQ mount. I have a Losmandy G11 mount, so most of your comments re "append on sync" and adding sync points don't apply - I can't see any facility in Alignmaster to do this with my mount.

I have used Alignmaster only when my mount has not been previously aligned. In Losmandy terms, this is a "Cold Start". It made no sense to me to have it aligned prior to using Alignmaster as the whole idea of AM is to minimize the physical alignment error prior to syncing the mount. The sync operation should remove any lingering alignment errors.

For me, I have had only one good experience with AM and one bad one. I probably should try again a few more times. It's disconcerting that AM shifts both axes at the correction stage (my reason for this posting), but I can live with it. I'm still getting a better physical alignment with it than without it.

As I observe further behaviour of AM I shall report it here in the interests of helping others.

Clear skies,
Paul.
BTW I wish one could choose an English-English spell checker on this site. (Just me grumbling ... please ignore. :-) )