Polar alignment.

[BillKinn]

Hello everyone, I'm wondering if I could get some help, sort of ripping my hair out a little.

I have the EXOS2 PMC-8 and last night I used Sharpcap to Polar align, I set the mount up as usual and adjusted until Sharpcap said excellent Polar alignment.

So my next step was to do a 3 star alignment  I was using a program called Explorer Stars to achieve this, so when I asked the mount to slew to the first star it was way off even in the finder scope, is that normal? So I used the controls to get the star in my FOV and centred it, it was the same for the next two stars way off. so I did the same.

I finished the 3 star alignment and when I asked the mount to find an object the object was not centred it was bottom right of the quick photo I took.

I've made sure all the information is correct by setting my Longitude and Latitude and also made sure my time is correct, the mount is balanced and level and pointing North. I think I'm doing something wrong somewhere.

Also may I ask should my counterweight bar be parallel with the mounts front leg? I have two little arrows on the mount that should be pointing at each other when in the home position but when they are the counterweight bar is pointing to the right quite a fair bit.

I'm new to all this only been doing it for a few months so a lot of things are quite confusing.     

Thanks in advance Bill. 

 

 

 

 

[Neil H]

Hi a lot of the goto systems have PAE i use synscan i found if you clear its memory then do 3 star alignment  if the first target after alginment is off i press esc then press and hold esc it asks me to centre  target which i do then press enter it stores it in PAE the next target is spot on your goto may have same sort of PAE and needs to be cleared and re done

[BillKinn]

2 minutes ago, Neil H said:

Hi a lot of the goto systems have PAE i use synscan i found if you clear its memory then do 3 star alignment  if the first target after alginment is off i press esc then press and hold esc it asks me to centre  target which i do then press enter it stores it in PAE the next target is spot on your goto may have same sort of PAE and needs to be cleared and re done

Hi thanks for the reply I don't use a handset as the PMC-8 box is connected to a laptop where everything is controlled via software, I reset the alignment data each time I use it.

[Neil H]

Hi sorry i could not help still learning this hobby 

[BillKinn]

2 minutes ago, Neil H said:

Hi sorry i could not help still learning this hobby 

I'm in the same boat, it's a steep learning curve.

[StevieDvd]

Hi Bill welcome to SGL,

We will try and help getting you up to speed.

It appears that you have polar aligned the scope which is the hard part.  The computer star alignment is based on your mount being in the correct home position and having the date and long/lat set correctly.  If any of these are out then it will not take you to chosen alignment point correctly.

Basically the scope would be pointing up (12 o'clock position if you think of the scope being the hands of the clock), whilst the weights would be vertical (or at the lowest point of the arc when the mount is moved). Some mounts have scales that can be set to show this as zero against a mark on the mount and can be adjusted by loosening a locking screw.

So if the date is set correct (it may want date in US format) and the long/lat/time is set correctly try with the weights parallel with the leg and see if that gets you nearer to the first alignment star.  If it does and the remaining alignments and goto stars are OK then tell the mount to park in home position and mark that position for next time (some tape and a marker pen).

See this page for an idea of how to set your home position starting point.

Edited October 7, 2020 by StevieDvd
Added link

[BillKinn]

20 minutes ago, StevieDvd said:

Hi Bill welcome to SGL,

We will try and help getting you up to speed.

It appears that you have polar aligned the scope which is the hard part.  The computer star alignment is based on your mount being in the correct home position and having the date and long/lat set correctly.  If any of these are out then it will not take you to chosen alignment point correctly.

Basically the scope would be pointing up (12 o'clock position if you think of the scope being the hands of the clock), whilst the weights would be vertical (or at the lowest point of the arc when the mount is moved). Some mounts have scales that can be set to show this as zero against a mark on the mount and can be adjusted by loosening a locking screw.

So if the date is set correct (it may want date in US format) and the long/lat/time is set correctly try with the weights parallel with the leg and see if that gets you nearer to the first alignment star.  If it does and the remaining alignments and goto stars are OK then tell the mount to park in home position and mark that position for next time (some tape and a marker pen).

See this page for an idea of how to set your home position starting point.

Thank you this is very helpful, I'm starting to think it maybe a home position issue, so definitely going to try what you suggested.  

Thanks again.

[Synchronicity]

For setting the weight bar vertical I first set it horizontal using a spirit level, adjust the setting ring (don't know the proper name) to zero, then rotate the bar 90 degrees.

Simple but accurate.

Michael

[Jamgood]

If you're using a computer to control, look at Plate Solving and you can forget about 2 or 3 star alignment. 

 

[StevieDvd]

21 minutes ago, Synchronicity said:

For setting the weight bar vertical I first set it horizontal using a spirit level, adjust the setting ring (don't know the proper name) to zero, then rotate the bar 90 degrees.

Simple but accurate.

Michael

That's how I did mine but I cheated and added a lnk with pictures that shows this method 🙂

[Synchronicity]

1 hour ago, StevieDvd said:

That's how I did mine but I cheated and added a lnk with pictures that shows this method

That's what I get for not reading the thread properly 😳  Where's the D'oh smiley face😁😁

[BillKinn]

Hi all I thought I would come back with a little update.

So after following the tutorial that StevieDvd posted (thanks for that mate) I figured out that in fact it was my home position that was the problem. The two little arrows that are meant to point at each other are way off. I uses Sharpcap to do another Polar alignment and set my RA to the new home position and all objects are bang in the middle of my view.

It's amazing how much it was off so I guess the little arrows are just for reference. I've marked the mount for future reference and for anyone with the EXOS-2 mount that's experiencing the same problem I would suggest to do as I did.

Thanks again for all the help.

Bill.

[smashing]

On 07/10/2020 at 14:44, Synchronicity said:

For setting the weight bar vertical I first set it horizontal using a spirit level, adjust the setting ring (don't know the proper name) to zero, then rotate the bar 90 degrees.

Simple but accurate.

Michael

Good lord I've never even thought of doing that before lol