I was searching the internet for polar alignment methods at high focal lengths. I can’t find a standard method for this.So, what do you prefer? (Assuming you do it with the high focal length scope..)
Polar alignment at high focal length
Polar alignment methods
2% (3 votes)
19% (32 votes)
35% (57 votes)
8% (13 votes)
5% (9 votes)
7% (12 votes)
4% (7 votes)
16% (27 votes)
3% (5 votes)
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I use N.I.N.As Three Point Polar Alignment with my EdgeHD 9.25 and OAG. Works great 
I've used SharpCap before and that also works fine.
I've used SharpCap before and that also works fine.
Lasse Skov:
I use N.I.N.As Three Point Polar Alignment with my EdgeHD 9.25 and OAG. Works great
I've used SharpCap before and that also works fine.
No issues from small FOV good!
C8HD + x0.7 + 533，NINA TPPA works find for me.
High focal lengths and polar alignment have nothing in common except, to a degree, for the declination drift method which wasn't explictly mentioned in the poll (hence my "Else" vote). This is really immaterial as long whatever your chosen method is, delivers 1' error or less in PA. Everything else depends on the quality of the mount and the amount of other mechanical errors you have in your rig. Most importantly, it (the requirement for a very good PA) depends on how good is your guiding/tracking system in coping with variable DEC and RA drift.
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Been using SharpCap and NINA on my C11" EdgeHD @ f/10 (2800mm) - no problem at all.
andrea tasselli:
High focal lengths and polar alignment have nothing in common except, to a degree, for the declination drift method which wasn't explictly mentioned in the poll (hence my "Else" vote). This is really immaterial as long whatever your chosen method is, delivers 1' error or less in PA. Everything else depends on the quality of the mount and the amount of other mechanical errors you have in your rig. Most importantly, it (the requirement for a very good PA) depends on how good is your guiding/tracking system in coping with variable DEC and RA drift.
Thanks for your answer. I will add it
RC10 @2000mm FL with 1 inch sensor and I use NINA TPPA, works good.
Polemaster for precise alignment of your mount versus your telescope. Simply works every time - in just minutes.
NINA 3 point works well. I like sharpcap just a bit better as I don't have full sky access to the north.
EKOS is also not on your list, but its the one I use with my RC-10 and also with my shorter Takahashi.
EKOS works very well too.
EKOS works very well too.
And I use the PA routine in ASIAir with my 10” at 3000mm. Reliable and no issues.
MaksPower:
And I use the PA routine in ASIAir with my 10” at 3000mm. Reliable and no issues.
At such high focal lengths, what is the typical error during polar alignment? And what is the typical guiding error do you see?
I am curious because I am really scared of moving to high focal lengths. I generally polar alignment to within 20" accuracy. The guiding errors I get are generally (overall) 0.7-0.9". On good or lucky days, I may get 0.5" also, but there are terrible days when the guiding error is high as 1.2-1.4"
As of now, I am just getting comfortable with 400mm focal lengths!
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You might try doing your guiding through a 25A red filter. It made a world of difference for me. I tried it for the first time last night and had an average guiding RMS over 6 hours of 0.14".
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I am really scared of moving to high focal lengths.
As of now, I am just getting comfortable with 400mm focal lengths!
I think moving up in focal length gradually is a good idea.
when people start imaging with a 2000mm SCT, thats a recipe for failure (generally) or at least a miserable learning curve.
I started at 448mm and then went to 530, followed by 714mm and finally to 1484mm.
each step forced me to learn something. and I needed to upgrade the mount for the last jump.
if you do things gradually its easier to understand the challenges and solutions.
Dont be afraid of it though, if I can do it anyone can.
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I didn’t have my choice for PA on the poll. I am using my Asiair plus to get it performed perfectly. Less than an arc sec on both axis. My rms runs .3 to .5.
I optically align my scope and average about 0.6" error, I get zero drift over 20 minute exposures.
MaksPower:
And I use the PA routine in ASIAir with my 10” at 3000mm. Reliable and no issues.
At such high focal lengths, what is the typical error during polar alignment? And what is the typical guiding error do you see?
I am curious because I am really scared of moving to high focal lengths. I generally polar alignment to within 20" accuracy. The guiding errors I get are generally (overall) 0.7-0.9". On good or lucky days, I may get 0.5" also, but there are terrible days when the guiding error is high as 1.2-1.4"
As of now, I am just getting comfortable with 400mm focal lengths!
Guiding at 3000mm the rig is basically chasing the seeing and that has nothing to do with poor PA. I've deliberately tried guiding with much larger PA errors - degrees - and the result is field rotation, that's all. Aligned within 2 arc minutes is sufficient to ensure PA is not an issue, and with the CQ350 alignment within 30 arcsecs is quite usual. At f/12 guide stars are around 4-5 pixels FWHM.
Guiding my "small scope" (MN65) is at 900mm focal length and likewise that is resolving (and trying to follow) the seeing - stars in the guide camera are typically 2 pixels FWHM. The CQ350 is very responsive in both axes - with negligible backlash in dec - and I found setting the guider cycle time very fast (0.2 sec) resulted in it chasing the seeing, whereas extending the cycle time to 2-3 seconds averaged-out the seeing with better results.
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Tony Carro:
I am using my Asiair plus to get it performed perfectly.
Less than an arc sec on both axis.
Hi Tony.
I would hazard a guess that you are referring to Arc Minutes.
I dont think any Polar Alignment is that accurate. 1 arc second is 1/36000ths of a degree for reference.
Experts can advise us on this.
I just use my polar alignment scope on my Mach 2…gets plenty close for extended imaging sessions and takes under a minute. Years ago, I used my Polar alignment scope on my Tak NJP and it was also more than sufficient for imaging. That's why I selected "else" since I didn't see PAS as an option.
I use the ASIAIR, hence selectiong else in the poll.
Focal length doesn't matter. We polar align the mount, not the telescope. That's why a polemaster makes absolute sense. 440mm, 860mm, 1625mm - all the same polar alignment for the mount itself. Cheers!
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I used to trust my PoleMaster until NINA came up with the Three Point Polar Align, which showed me how far away from good polar alignment I was. I decided to keep the PoleMaster just to get a good approximation, but then I use NINA for fine tunning it.
My mount has iPolar. Works great! Nice to be able to PA without being dependent on NINA and having that working.
In current use, my longest scope is 980mm. With an ASI2600MC, the ASIAIR Plus has no problems plate solving. With an ASI533MC, plate solving struggles.
When I was occasionally using my 10" RC at 2,032mm, plate solving really struggled, especially with the 533.
So, in that I can (and do) use a 360mm guide scope, I just polar align through the guide scope as my main camera, then switch back.
Presto !! No problems there. No problems in my main scope images ....
When I was occasionally using my 10" RC at 2,032mm, plate solving really struggled, especially with the 533.
So, in that I can (and do) use a 360mm guide scope, I just polar align through the guide scope as my main camera, then switch back.
Presto !! No problems there. No problems in my main scope images ....
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