Polar scope on AVX?

[Alan White]

Having been blessed with a few clear nights since buying my AVX mount over the past six weeks, yep that much cloud.

I have found the open polar axis with no scope has allowed fairly good polar alignment, however (always a however), I am not as accurate as I wish even for visual use, so now looking at a polar scope.

Too skint for any camera options at present, so the scope or nowt are the options.

Is this a worthy spend and if yes, should I add an illuminator?

As always your help and input will be much appreciated.

 

[gonzostar]

Yes its worthy of a spend especially with the illuminator. I had one before i got pole master It did help me get close to PA, but then i needed to do drift alignment using PHD2

[Starlight 1]

8 minutes ago, gonzostar said:

drift alignment using PHD2

Have you try phd2 dev 3 that have got PA on it.

[gonzostar]

No i didnt. I went straight for the polemaster and havent looked back since  

[John]

I bought a polar scope when I had an AVX. The issue that I found was, when the scope was fitted, one of the latitude locking knobs was positioned so that I could not get my head and eye close the the eyepiece of the solar scope

I think I would have needed a RA adapter for the polar scope to be able to use the thing.

 

[triton1]

With my Cg5 I just shine a red light over the opening no need for a illuminater.

[newbie alert]

Try the ASPA Alan 

[Olsin]

1 hour ago, John said:

I bought a polar scope when I had an AVX. The issue that I found was, when the scope was fitted, one of the latitude locking knobs was positioned so that I could not get my head and eye close the the eyepiece of the solar scope

I think I would have needed a RA adapter for the polar scope to be able to use the thing.

 

I had exactly the same problem John. I had installed them as per the manual with the long handled one at the rear and the shorter butterfly like grip one at the front. My solution was to simply switch the latitude locking nuts around. The long gripped one has no detrimental effect being at the front, while the short butterfly gripped latitude knob enables a clear, unobstructed view through the PA scope.

@Op ... A PA scope has to be carefully aligned to the mount before you can use it. I've spent hours twiddling about with mine although the best i've ever achieved was still ever so slightly off. For this reason, i can't use it to get a good PA.

I find ASPA on my AVX while initially horrendous when i first started using it, has improved greatly now that i have had more time to hone setup and alignment routines.

[PeterCPC]

ASPA (if done properly) will give a good PA.

Peter

[PeterCPC]

This was the checklist that I used for ASPA before I got my Polemaster.

Peter

Telescope Set Up Checklist.docx

[Olsin]

12 hours ago, PeterCPC said:

This was the checklist that I used for ASPA before I got my Polemaster.

Peter

Telescope Set Up Checklist.docx

Yes that's a good quick guide Pete although a typo probably makes it a little confusing for someone who's not tried it before.
The quick guide reads like this..

Polar Alignment
1.Slew to bright star high and near meridian.(not overhead)
2.Press Align – Polar Align – Align Mount.
3.Scope will slew away and back.
4.Centre star in finder – Enter – centre star in EP. Scope will sync.
5.Enter – Use Lat and AZ bolts to centre star – Enter

There stands an "Enter" where it should be "Align". It should read..

4.Centre star in finder – Enter – centre star in EP - "Align". Scope will sync and then slew away and back
5.Use Lat and AZ bolts to centre star – Enter

 

[Olsin]

Oh dear, i made a mistake as well. Instead of amending the quick guide again and making it even more confusing i'll just copy and paste the whole amended guide below.

Peter ... If for some reason the original alignment stars aren't visible when you get to updating the star alignment (gone behind tree's, houses etc), would a power down and restart with 2 + 2/3/4 achieve the same results? As long as the mount isn't moved it would still be PA'd.

Peters AVX quick guide:

Initial Alignment
1.Level, point North, set to Home position.
2.2 star align with calibration steps

Polar Alignment
1.Slew to bright star high and near meridian.(not overhead)
2.Press Align – Polar Align – Align Mount.
3.Scope will slew away and back.
4.Centre star in finder – Enter – centre star in EP - Align. Scope will sync and slew to where the star is if mount was polar aligned.
5. Use Lat and AZ bolts to centre star in EP – Enter

Updating Star Alignment
1.Press Align – Undo sync – Enter
2.Slew to one of the original alignment stars.
3.Press Align – alignment stars – select star.
4.Centre star – Enter- Align.
5.Repeat for other Alignment star.
6.Slew to bright star on opposite side of Meridian.
7.Press Align – Calib stars – Enter.
8.Centre star – Enter – Align.
9.Press Back – Align – Polar Align – Display Align.

 

 

[PeterCPC]

I never powered down when I did an ASPA so I can't answer that. If the original alignment stars are not visible I believe that you can just use other visible stars.

Peter

[Luna-tic]

On ‎10‎/‎19‎/‎2017 at 16:16, triton1 said:

With my Cg5 I just shine a red light over the opening no need for a illuminater.

This is what I've always done with the PA scope on my Astroview (non goto) mount. Works just fine, although you have to play with with the angle that you play the light into the front of the scope. Just bought the CG5 PA scope for my AVX, got it aligned with the RA axis, gonna see tonight how much better an alignment I can get than just looking through the empty hole where it fits.

On ‎10‎/‎19‎/‎2017 at 16:08, John said:

I bought a polar scope when I had an AVX. The issue that I found was, when the scope was fitted, one of the latitude locking knobs was positioned so that I could not get my head and eye close the the eyepiece of the solar scope

I think I would have needed a RA adapter for the polar scope to be able to use the thing.

 

I wonder if that's an issue with the latitude you're at, having more of the knob sticking back. At 35 degrees N.Lat, I don't have an issue with mine poking me when I sight through it.

8 hours ago, Olsin said:

Oh dear, i made a mistake as well. Instead of amending the quick guide again and making it even more confusing i'll just copy and paste the whole amended guide below.

Peter ... If for some reason the original alignment stars aren't visible when you get to updating the star alignment (gone behind tree's, houses etc), would a power down and restart with 2 + 2/3/4 achieve the same results? As long as the mount isn't moved it would still be PA'd.

 

 

 

If you power the mount down and your previous alignment was okay, just choose "last alignment" when you power back up, as long as you haven't moved the mount. Make sure your time and date are accurate, it should still be an accurate alignment. When I go out early, then go inside for a while, I power down the mount to save my battery. When I go back out a few hours later to view early morning objects, I just choose "last alignment" and it's right on the money, usually. At least within the FOV. Then I can update it by synching on the first couple of objects I look at.

[newbie alert]

You can  hibernate..go to home position..go to hibernate mount  which I think is utilities..powet off...then when you switch back on you can "wake up" re do the time/date and you're good to go 

[PeterCPC]

If you want accurate PA you should always use an illuminated reticule eyepiece - I use a 12mm and don't change the eyepiece once the process has begun. Also make sure that all final adjustments are to the right and up.

Peter

[Olsin]

15 hours ago, Luna-tic said:

If you power the mount down and your previous alignment was okay, just choose "last alignment" when you power back up, as long as you haven't moved the mount. Make sure your time and date are accurate, it should still be an accurate alignment. When I go out early, then go inside for a while, I power down the mount to save my battery. When I go back out a few hours later to view early morning objects, I just choose "last alignment" and it's right on the money, usually. At least within the FOV. Then I can update it by synching on the first couple of objects I look at.

No not quite. The mount will already be star aligned after start up and a 2+4. After running the ASPA routine the mount will have been moved so the original star alignment is now inaccurate. To sort out this inaccuracy the original calibration stars are re-aligned.

My question was that if for some reason the original calibration stars are unavailable, would a power down and redo 2+4 achieve the same result as recalibrating the original calibration stars?

If i powered down and restarted using "last alignment" the mount will just initialise the last inaccurate alignment (because the mount had been PA'd after the initial alignment).

3 hours ago, PeterCPC said:

If you want accurate PA you should always use an illuminated reticule eyepiece - I use a 12mm and don't change the eyepiece once the process has begun. Also make sure that all final adjustments are to the right and up.

Peter

I use a 20mm 70 degree illuminated reticule EP for all alignments. I tried a 12mm but often the target star wasn't in the FOV and i'd have to put a 25mm EP back in to get the star closer to the middle before reinserting the 12mm to get it spot on. I felt that the constant swapping of EP's would have a negative effect on accuracy. Now the 20mm stays in from start to finish and is only swapped out once all alignments are completed. The last 2 stars of a star alignment are usually almost spot on the reticule..

 

[PeterCPC]

I found that if I used a 40mm EP for the very first step to centre the first star and then put the 12mm IR EP in, I could leave it in from then on as the target stars were always then in the FOV. A 20mm IR EP would work as well but I could not find one at the time.

Peter

[Alan White]

Thanks for all the information, having read this and based on what I asked,
I have ordered a polar scope via FLO and will also be looking at an IR EP, just unsure on which one as of yet.

[Luna-tic]

5 hours ago, Olsin said:

No not quite. The mount will already be star aligned after start up and a 2+4. After running the ASPA routine the mount will have been moved so the original star alignment is now inaccurate. To sort out this inaccuracy the original calibration stars are re-aligned.

My question was that if for some reason the original calibration stars are unavailable, would a power down and redo 2+4 achieve the same result as recalibrating the original calibration stars?

If i powered down and restarted using "last alignment" the mount will just initialise the last inaccurate alignment (because the mount had been PA'd after the initial alignment).

 

 

I don't understand doing a PA after an initial star alignment. A precise PA is important to even get a star alignment. I always do a careful PA during initial setup, even before mounting the tube: orient tripod to basic celestial North (I use a compass and then account for the magnetic declination) and level it, install the mount and use the scope to  align it to Celestial North, adjusting alt and az as needed for location. Then I install the tube and accessories, balance it, and then do a 2-star alignment and maybe one calibration star. After that, the objects I select are always within the FOV (I generally start with a 25mm EP). After bouncing around the sky a while, I may get some drift, so I'll update the alignment after 5 or 6 objects. My entire initial setup, PA and star alignment takes about 15 minutes.

I can shut down, restart later in the evening (or early morning) and when I use "last alignment", I'm usually within the FOV or just a few degrees out, and an update gets me back. Restarting and choosing 'last alignment' requires returning the Dec and RA axes to the starting point (marks aligned). Of course, anything that disturbs the initial polar alignment (moving the tripod), and everything is off.

[Olsin]

1 hour ago, Luna-tic said:

I don't understand doing a PA after an initial star alignment. A precise PA is important to even get a star alignment. I always do a careful PA during initial setup, even before mounting the tube: orient tripod to basic celestial North (I use a compass and then account for the magnetic declination) and level it, install the mount and use the scope to  align it to Celestial North, adjusting alt and az as needed for location. Then I install the tube and accessories, balance it, and then do a 2-star alignment and maybe one calibration star. After that, the objects I select are always within the FOV (I generally start with a 25mm EP). After bouncing around the sky a while, I may get some drift, so I'll update the alignment after 5 or 6 objects. My entire initial setup, PA and star alignment takes about 15 minutes.

I can shut down, restart later in the evening (or early morning) and when I use "last alignment", I'm usually within the FOV or just a few degrees out, and an update gets me back. Restarting and choosing 'last alignment' requires returning the Dec and RA axes to the starting point (marks aligned). Of course, anything that disturbs the initial polar alignment (moving the tripod), and everything is off.

 

It's possible i've misunderstood Celestrons instructions with my AVX but it has always seemed to me that you first do the initial setup including a 2+4 star alignment and then ASPA afterwards followed by a realignment. I agree that it's long winded. A handset routine that allowed an (AS)PA first and then a star align routine would be preferable.
I also do a basic PA first by using my polar scope together with a PA App. It's kinda close but by then doing a 2+4 followed up with an ASPA, i always have to adjust lat/az a bit which shows that the polar scope wasn't dead accurate.
At the end of the day i guess a lot depends on the focal length you're working with plus what you plan to be doing. A 2+1 star plus rough PA is plenty sufficient if you're only doing visual. I can't imagine that being anywhere near good enough if you wanted to image though, especially at higher focal length's.
As for hibernating my setup or using last alignment. Just like many others, i setup and break down after every session. I just set up (usually while it's still light) and get all the alignments out of the way before the sky gets really dark. Then i'll do whatever i'm doing until i feel the session has ended. If clouds come in or i just fancy a cup of tea i might leave the setup for 30 mins or so but i'll always center on a star before leaving. When i get back i can see how far the star has drifted of center and judge if i want to do something about it or not.
More often than not though, i'll leave it as long as the star is in FOV. I'm just enjoying visual astronomy atm...imaging can wait until i get a different scope.

[Filroden]

1 minute ago, Olsin said:

It's possible i've misunderstood Celestrons instructions with my AVX but it has always seemed to me that you first do the initial setup including a 2+4 star alignment and then ASPA afterwards followed by a realignment. I agree that it's long winded. A handset routine that allowed an (AS)PA first and then a star align routine would be preferable.

ASPA can only work if the scope knows how it is aligned. That's why you need to do a star alignment first.

[Olsin]

1 minute ago, Filroden said:

ASPA can only work if the scope knows how it is aligned. That's why you need to do a star alignment first.

Then i hadn't misunderstood the manual..

[PeterCPC]

No.

Peter

[Alan White]

On 10/19/2017 at 23:14, Olsin said:

I had exactly the same problem John. I had installed them as per the manual with the long handled one at the rear and the shorter butterfly like grip one at the front. My solution was to simply switch the latitude locking nuts around. The long gripped one has no detrimental effect being at the front, while the short butterfly gripped latitude knob enables a clear, unobstructed view through the PA scope.

@Op ... A PA scope has to be carefully aligned to the mount before you can use it. I've spent hours twiddling about with mine although the best i've ever achieved was still ever so slightly off. For this reason, i can't use it to get a good PA.

I find ASPA on my AVX while initially horrendous when i first started using it, has improved greatly now that i have had more time to hone setup and alignment routines.

And now I have a Polar scope I see the problem, a mount that when a Polar scope is fitted is unusable with the manufacturer's bolts, what a stupid bit of design or lack of design by Celestron!
I will get a suitable bolt made up to resolve this.

AS to Polar scope alignment, surely its better than best guess through the open bore?

ASPA no doubt will enter my life one day very soon, sounds like a royal pain at the start.