User error?

Using SharpCap's Polar Alignment feature
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User error?

Post by Lookinup » Sat May 06, 2017 8:45 am


I hope someone can help me with this issue I was getting last night. Having activated Polar Alignment, the software selected enough stars to allow the 'next' button to be pressed. When then moving the RA access 90° ( I think I might be a bit short on the full 90 because of housing obscuring the full 90°, I would guess at 80 to 85°) the number of stars available show as fluctuating between 30 and 40 with 15 being used for the alignment process, however... that's all that happens, the system does NOT freeze, or hang, but does not move to the next stage in the process.
So the question, how long does it take for the screen to move on to the adjustment screen? and being just short of the 90°, will this effect the program moving on?
My mount is on a pier so will be impossible to relocate to a different position which would afford full, clear views to 90°.

Thoughts and any help will be most appreciated!

Using SharpCap 3.0



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Re: User error?

Post by admin » Sat May 06, 2017 10:46 am

Hi Phil,

first question would be - did you press the 'Next' button when it went green to move to stage 2? I assume you did, but it's always worth asking :)

Once you get to stage 2, you will see this sort of view in the Polar Align work area
Capture.PNG (25.98 KiB) Viewed 268 times
What you need to be looking at is the 'Second Frame' area to see if SharpCap has got a plate solve solution for the rotated frame - look at the Status and the Rotation readouts. You can also look at the left hand side to see the plate solve status of the most recent frame that has been processed. Once you have a solved status for the second frame with a big enough rotation the 'Next' button will go green to allow you to move to step 3. I think the rotation has to be about 40 degrees or more, but near 90 is best.

If you are getting plenty of detected stars in the second frame status box and still no solution then you could try tweaking exposure/gain on the camera, or pressing the 'restart' button *without* rotating back to the first orientation. By restarting in the rotated position you get to play with the star detection tweaks in step 1 until you can get a good plate solve in that rotated position - then you can rotate back and should be fine.

If you want to get a feel for what you are doing then you can simulate the PA procedure using Test Camera 1. Here are the steps...

* Download the two sample frames from this message - horiz_0001 and vert_0001
* Open SharpCap and select Test Camera 1 (Deep Sky)
* Expand the 'Testing Controls' section in the controls and click on the 'Browse' button next to 'Image' at the top of the list
* In the open file dialog, select 'All Files (*.*)' from the drop down instead of Image Files, otherwise you won't see the JPG files to open them
* Select either of the jpg files - it will show in SharpCap as if you had a camera showing that image
* Choose Polar Align from the menu
* You should get the green button to move to step 2 within a few seconds, press it
* Press the browse button again and select the other file (so if you used horiz_0001 the first time now choose vert_0001)
* The next button should become enabled within a second or too - you'll also see the 'Second Frame' status become filled in
* Press the next button and you will see the adjustment arrow appear and you can see what the final phase of the PA procedure should look like

You obviously can't make real adjustments to make the arrow shorter when you are testing this way, but you can switch on the 'Random Offset' control in the 'Testing Control' section on the right which makes small random position changes to the camera frame being shown - this will show at least a little bit how the arrow will change as you adjust your alt/az bolts when doing this for real.


vert_0001.jpg (100.65 KiB) Viewed 268 times
horiz_0001.jpg (101.55 KiB) Viewed 268 times

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Joined: Sat May 06, 2017 8:08 am

Re: User error?

Post by Lookinup » Sat May 06, 2017 12:38 pm

Hi Robin

Thanks for your prompt reply!

Thanks for the tips and for the walk through using the test environment!, much appreciated that I can see first hand what the process should look like..
When I got to the second frame to solve and couldn't I was essentially just going back and trying the process again.... and of course then getting stuck at the same point.
Fingers crossed I will have a clear sky (although a 85% lit moon!) and will try playing about with the camera settings to resolve the picture, I'll keep you posted!

Thanks again Robin.


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