Polar scope frustrations

[Adam1234]

I'm having a few problems with the polar scope in my Meade LXD75 mount, maybe someone can offer some advice.

The reticle in the polar scope never seems to keep alignment to the RA axis. I aligned the polar scope to the RA axis the other day, during the daytime, following this tutorial: 

https://www.myastroscience.com/polarscopecalibration

A couple days later I took it outside to have a go at polar alignment, and went to double check that the polar scope was still aligned and it was massively off. I spent a bit of time aligning it, to the point where Polaris (which I was using the align the polar scope) stayed right under the crosshairs when I rotated the RA axis.

I've just taken it outside now to polar align, and again, thought it double check the alignment of the polar scope to the RA axis, and it is massively off again??

Ive read that this bit only needs to be performed once. Is there something I'm doing wrong here? 

Edited January 19, 2020 by Adam1234

[Adam1234]

The 3 screws used to adjust the reticle are in quite tight and there is no movement of the polar scope if I wiggle it.

[Alien 13]

I had this problem when I swapped the original grub screws on my polar scope for thumbscrews, soon swapped back.

Alan

[teoria_del_big_bang]

So long as the polar scope is tight and cannot move with respect to the RA axis then using that alignment process it should be spot on.

Without adjusting anything are you saying that if you check it again to a terrestrial target in daytime, as in the link, then it is not aligned anymore?

Steve

 

Edited January 19, 2020 by teoria_del_big_bang

[Adam1234]

17 minutes ago, teoria_del_big_bang said:

 

Without adjusting anything are you saying that if you check it again to a terrestrial target in daytime, as in the link, then it is not aligned anymore?

Steve

 

Hi Steve

Yes exactly, so I followed that process during the daytime, and got the reticle aligned to the RA axis. Then checked it again a few days later and it wasn't aligned anymore and had to repeat the process. And now I've just had to do it again. 

Is there something else inside the polar scope which could be loose?

[teoria_del_big_bang]

I am not familiar with your mount but looking at this tutorial it looks very easy setup and not indifferent from my HEQ5.

Meade LXD75 Mods and How to's #4 Polar Alinement part 2

So if you are sure none of the 3 adjustment screws are moving and it is all tight around those screws then I can only assume something at the other end of the polar scope is moving. Any signs of any wear of marks if you remove the polar scope altogether.

Steve

[Adam1234]

16 minutes ago, teoria_del_big_bang said:

I am not familiar with your mount but looking at this tutorial it looks very easy setup and not indifferent from my HEQ5.

Meade LXD75 Mods and How to's #4 Polar Alinement part 2

So if you are sure none of the 3 adjustment screws are moving and it is all tight around those screws then I can only assume something at the other end of the polar scope is moving. Any signs of any wear of marks if you remove the polar scope altogether.

Steve

I'll remove the polar scope during the week and investigate.

I've just had a thought actually. I wonder if the polar scope itself is loose, but seeming to be held in place by the reticle, but then moving around when the telescope is moved.  When I first bought the scope/mount (second hand), the polar scope was loose and wobbling around and I could pull it out somewhat. Tightening the 3 screws seems to hold it in place, but perhaps I'm right in saying that all I done was tighten the reticle around the polar scope and made it appear that the polar scope is tight, and maybe there should be other screws that I should have tightened? 

I don't know if that makes sense to you at all.

Edited January 19, 2020 by Adam1234

[teoria_del_big_bang]

32 minutes ago, Adam1234 said:

I'll remove the polar scope during the week and investigate.

I've just had a thought actually. I wonder if the polar scope itself is loose, but seeming to be held in place by the reticle, but then moving around when the telescope is moved.  When I first bought the scope/mount (second hand), the polar scope was loose and wobbling around and I could pull it out somewhat. Tightening the 3 screws seems to hold it in place, but perhaps I'm right in saying that all I done was tighten the reticle around the polar scope and made it appear that the polar scope is tight, and maybe there should be other screws that I should have tightened? 

I don't know if that makes sense to you at all.

Sounds like that is the way to go. 

There has been a lot of things in this business that for a while have not made sense, but there is always a reason and when you find it it THEN all makes sense 🙂 

Good luck I hope it all becomes blindingly obvious.

Steve

[Adam1234]

27 minutes ago, teoria_del_big_bang said:

 

Good luck I hope it all becomes blindingly obvious.

Steve

Thanks!  A few adjustments and I got the reticle aligned again at least for this evening, and polar aligned as best as I can, good enough for a set of 30s subs of M42 anyway. See how the final image looks tomorrow.

Hopefully figure out the issue with the polar scope during the week so I don't have to keep aligning it every time.

[g-rex]

I have this same issue with my eq3-2.

If you ever find the answer please let us know! 

[Nigella Bryant]

I've a neq6, I discarded using the polar scope and use sharpcap polar align and for £10 a year isn't even worth worrying about. It's so easy and done in a matter of minutes and spot on. Just a thought. 

[Adam1234]

1 hour ago, g-rex said:

I have this same issue with my eq3-2.

If you ever find the answer please let us know! 

Will do!!

[Adam1234]

1 hour ago, Nigella Bryant said:

I've a neq6, I discarded using the polar scope and use sharpcap polar align and for £10 a year isn't even worth worrying about. It's so easy and done in a matter of minutes and spot on. Just a thought. 

Sometime in the future I will probably use sharpcap, but I don't have a dedicated astronomy camera yet. I'll save up some money for one.

[JamesF]

2 hours ago, g-rex said:

I have this same issue with my eq3-2.

If you ever find the answer please let us know! 

I'm sure I had the same problem with my EQ3-2.  As I recall, the upper end of the polar scope was free to move about inside the mount.  I think I fixed it by putting an O-ring around the top of the polar scope barrel to hold it in position against the inside of the mount.

James

[JamesF]

2 hours ago, Nigella Bryant said:

I've a neq6, I discarded using the polar scope and use sharpcap polar align and for £10 a year isn't even worth worrying about. It's so easy and done in a matter of minutes and spot on. Just a thought. 

I think it's easier to do with software, too.  I assume the OP is using a DSLR.  I don't know if SharpCap works with DSLRs, but if it does then I'd hope that would make it quite straightforward.  Unfortunately I don't think OpenPHD will work with a DSLR, but it also has support for polar alignment and can be used even if you have no view of the pole star.

James

[Nigella Bryant]

3 minutes ago, JamesF said:

I think it's easier to do with software, too.  I assume the OP is using a DSLR.  I don't know if SharpCap works with DSLRs, but if it does then I'd hope that would make it quite straightforward.  Unfortunately I don't think OpenPHD will work with a DSLR, but it also has support for polar alignment and can be used even if you have no view of the pole star.

James

Hi James, don't know about using a dslr, I use a zwo camera with the sharpcap. 

[g-rex]

2 hours ago, JamesF said:

I'm sure I had the same problem with my EQ3-2.  As I recall, the upper end of the polar scope was free to move about inside the mount.  I think I fixed it by putting an O-ring around the top of the polar scope barrel to hold it in position against the inside of the mount.

James

That's great advice! Thanks, I'll have a look at it 👍

[theeruditefrog]

 will post to another thread.

 

 

Edited May 1, 2020 by theeruditefrog

[Robindonne]

On 20/01/2020 at 16:57, g-rex said:

That's great advice! Thanks, I'll have a look at it 👍

That’s exactly how i tried to fix this issue.  I gave my daughter an LX75 mount and faced the same problem.  I did use a foam ring however.  To not have huge pressure on the barrel but to only have a small buffer for movements inside when the mount is moved.  Ive never checked it actually because her mount is not used at the moment.  I think it helps though 

Edited April 30, 2020 by Robindonne