Guide Scope Polar Alignment

Using SharpCap's Polar Alignment feature
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SonnyE
Posts: 9
Joined: Sat Apr 18, 2020 5:37 am

Guide Scope Polar Alignment

#1

Post by SonnyE »

Up until last night, I've been doing my Polar Alignment with my Main telescope and imaging camera (Atik Infinity OSC).
But a discussion with another brought up doing Polar Alignment using the Guide Scope and Guiding Camera, which was appealing to me being as I have a newer ASI 290 MM Mini guide camera. And have had some very refreshing results guiding with it.
So Last night I set Sharpcap to use the 290 as the PA camera.

It was a little bumpy at first, not unusual for me, but Sharpcap did accept the newer camera and I just randomly chose a 2 second exposure for the ASI 290 MM Mini to work with. My Infinity wanted a 4 second exposure and was always a bit iffy even at that. I did sharpen up the guide scopes focus (Helical Focuser) as I could see a lot of room for improvement to what I'd been using. And past experience with my Infinity had taught me sharp focus was best.
At first it had a little trouble solving, but I'm sure that was me, and not Sharpcap.
My first solve left me at step 2 (or3) and was not accomplishing a solve. I decided to do a restart, and my telescope was at it's 90° setting from the previous attempt. I decided to go ahead anyway and hoped I would wind up back at starting position, Counter Weight Down, at the finish of the Polar Alignment.
It worked, and it worked Admirably, ending at CWD. I achieved a better Polar Alignment, much faster, than I have ever experienced. Even though Sharpcap gives me it's "Excellent" at 00-00-20, I'm a fiddler. So I always see how close I can get to 00-00-00 on both Alt and Az. I love tickling the dragons tail that way.
The ASI camera was responding very well to minute adjustments, and Sharpcap let me get to an Az: 00-00-02 by Alt: 00-00-00 reading. As is typical for me, there is some minor atmospheric disturbances that will tend to make the finals bob a bit, but typically stay within single digits. I saw the 00-00-02 go to a maximum of 00-00-09, but was lower typically on subsequent image solves.

I admit to being a tinkerer and always trying for the ridiculous when it isn't needed, but to me it is fun. My conclusion after this first single excursion using my Guiding system to do my Polar Alignment is that I shall continue to always do my PA this way.
Because I am one to dismantle my equipment each night to bring it indoors, I start every night with a fresh Polar Alignment, then a new modeling before beginning my evening imaging.

I do suppose I have one question:
I'm wondering if I reduce the exposure time of the ASI 290 camera, how low can I go to speed up the solving without causing it to stumble?
Or is that something I will need to find by trial and error?

In closing, I find Sharpcap to be The Bee's Knees and has easily shot my ability to image DSO Nebulae to an entirely new level.
Thank You Mr. Robin Glover.

Sonny Edmonds
California, USA
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Re: Guide Scope Polar Alignment

#2

Post by admin »

Hi Sonny,

Glad to hear that you had such a good experience of using the polar alignment with the guide scope.

With respect to your question on the exposure, it's definitely going to be a bit of trial and error. If you haven't already got to maximum gain on the camera then by all means crank up the gain further and wind down the exposure to compensate – that will tend to keep the image brightness the same and mean that the polar alignment should continue to work (although the extra noise from higher gain may lead to a little more jumping around of the numbers). Once you've reached the maximum gain, any further reduction in the exposure puts you at risk of not being able to detect enough stars – that's the point where it becomes trial and error to see how low you can go while keeping things working reliably.

Cheers, Robin
SonnyE
Posts: 9
Joined: Sat Apr 18, 2020 5:37 am

Re: Guide Scope Polar Alignment

#3

Post by SonnyE »

Thanks Robin!
Sorry for such a delay getting back to this.
I did some trial and error tonight and found a good improvement with my equipment.
I tend to move slowly working up my equipment.
But when things begin to click together, they really worked great.
Very happy!
Thank You,
SonnyE
SonnyE
Posts: 9
Joined: Sat Apr 18, 2020 5:37 am

Re: Guide Scope Polar Alignment

#4

Post by SonnyE »

Hi
Just getting back to it after a bit of a medical lay-up.
But I finally am getting some of the cobwebs out of my head.
My basic problem is I have a single guide camera, single telescope, single mount....
But multiple profiles for the one camera (ASI 290 MM) I use to do my Polar Alignment and guiding with.
I finally realized the precise profile that works fantastic with Sharp Cap out of the 4.
One is a Copy, two others are not desirable.
So I would like to remove them from the Camera choices in the camera selection available.

But I cannot seem to find my way to do so. :roll: :oops:

Can anyone (Robin?) please help me with how to remove unwanted camera profiles in the Polar Alignment feature?
Things are working absolutely peachy, except for cleaning up a bit. I would like the PA to default to the one great profile.

Edit in:
And wouldn't you know, this evening I figured it out, delete miscellaneous capture profiles, and made my preferred profile the default.
It was there under the controls in the Manage icon. Then closed the program, and reopened it. All Hunky-Dory now.
Now, if the Sun would just set faster.... :lol: :roll:
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Re: Guide Scope Polar Alignment

#5

Post by admin »

Hi,

glad you got it sorted. Unfortunately speeding up sunset is not something SharpCap can help you with (sadly the same applies to clearing clouds away...)

cheers,

Robin
SonnyE
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Joined: Sat Apr 18, 2020 5:37 am

Re: Guide Scope Polar Alignment

#6

Post by SonnyE »

Thanks Robin!
Now that SharpCap has but one profile, for the one camera, it is working fantastic.
And since I am not dismantling my mount all the time, it holds Polar Alignment almost well enough to skip it.
But I never do skip my PA. I need the accuracy of a great Polar Alignment to set up my modeling, for great acquisition.
I particularly enjoy getting as close to all Zero's as I can with my ALT-AZ. Just perfection seeking.
Thank You for a great application, Robin!
mjd6191
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Joined: Thu Mar 19, 2020 12:44 pm

Re: Guide Scope Polar Alignment

#7

Post by mjd6191 »

I have a question regarding using the guide scope and camera for polar alignment. I know when guiding with PHD2, the guide scope and the main scope do not need to be perfectly aligned, but if you are using Sharpcap Polar Alignment do they need to be aligned? Or is the alignment related specifically to the mount?
I have the following setup:
Orion 8" 4.9 reflector (Skyview pro)
SVBony 60mm guide scope
ZWO ASI120MM-S Camera for guiding
SVBONY SV305 for planetary
Nikon d3400 used on occasion
I cannot use my main scope because the FOV is too small (.28° x .21°), my guide scope is right on the edge (1.15° x .86°) but should in theory work.

Can I polar align with this setup using Sharpcap, I find PHD2 drift alignment kindo of painful and want to try the Sharpcap method

Thanks in advance
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Re: Guide Scope Polar Alignment

#8

Post by admin »

Hi,

no need to worry about small errors in the alignment of the guide scope - the results are not affected (by small here, we are talking 1, 2, 3 degrees or less. If you are several degrees off then you will have problems...)

The thing you do need to be careful of is that the guide scope is firmly mounted, the camera is secure and any cables are tied in. If the guide scope or camera shift when rotated this will cause errors. The weight of a dangling cable can cause a shift that is noticeable in some cases.

cheers,

Robin
mjd6191
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Joined: Thu Mar 19, 2020 12:44 pm

Re: Guide Scope Polar Alignment

#9

Post by mjd6191 »

Thanks Robin,
I will tie all down and make sure it is secure (and wait until the moon isn't quite as bright) to test out!
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