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 Post subject: Computer-aided polar alignment
PostPosted: Tue Feb 07, 2017 11:39 am 
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Joined: Mon Oct 12, 2009 6:47 pm
Posts: 1235
Location: Bolton
Thanks to Carl for spotting that the latest versions of the free SharpCap program (http://www.sharpcap.co.uk/) include a polar alignment tool.
This program supports various cameras including Altair, ZWO, QHY and even converted webcams, and I was pleased to find that Version 2.9 even installs and runs on my old WindowsXP "scraptop" computers.

I fitted a 135mm lens to an old webcam and tried it out during the clear spell on Sunday night, managing to achieve a startlngly accurate alignment on an old EQ1 mount (after a lot of tweaking and nudging!).
Attachment:
polar8.png
polar8.png [ 236.83 KiB | Viewed 1539 times ]

A full write-up will follow in next month's newsletter.

This program should be a great help for those struggling to align a fork-mount on an EQ wedge!


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 Post subject: Re: Computer-aided polar alignment
PostPosted: Tue Feb 07, 2017 6:01 pm 
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Joined: Fri Sep 07, 2012 7:20 am
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Location: Atherton
Looking forward to trying this Ross. Mount attachment sorted and Sharpcap downloaded.


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 Post subject: Re: Computer-aided polar alignment
PostPosted: Wed May 03, 2017 7:25 pm 
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Location: Bolton
The recent problem with my polar-scope (see http://www.boltonastro.co.uk/forums/viewtopic.php?f=7&t=944) showed me how useful it would be to have an alternative method of checking and refining manual polar alignment, so this week I've been back to have another look at this project.

I'm now using an old Soligor 50mm lens on my Atik 1HS guide-camera, which gives a much better field-of-view than the 135mm lens which I'd used in February, and makes the system easier to set up and use.

Although I can do my initial alignment sighting Polaris in my polar-scope in the twilight, I need to wait until it gets properly dark before the camera can pick out the 7th-magnitude stars which it needs for its plate-solving. Then the program itself is quick and easy to use, but the fine-adjustment of the bolts on my tired old CG5 mount is the fiddly bit which takes all the time!


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 Post subject: A low-cost compact pole-camera
PostPosted: Thu May 11, 2017 7:46 am 
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Joined: Mon Oct 12, 2009 6:47 pm
Posts: 1235
Location: Bolton
I've been working with one of the Philips SPC880 webcams which I converted some years ago for long-exposure imaging. I've adapted it to run from a single USB port (so it no longer needs a separate COM port), and set it to run in RAW mode, which gives much sharper star images.

Experiments with my Atik 1HS camera (effectively a re-boxed Philips webcam) suggested that a 50mm focal-length would be best for a Pole-camera, so I was delighted to find this little lens with an M12 webcam fitting: http://www.ebay.co.uk/itm/1-3-039-039-50mm-6-7-Degree-M12-CCTV-MTV-Board-IR-Lens-for-Security-CCTV-Video-Cameras-/282467152884
It arrived from China within 10 days, and works really well - even without an IR-blocking filter the star-images are sharp enough for SharpCap's Star Detection process. And the complete camera and lens assembly is now small and light enough to attach to any convenient point on a mount, fork-arm or optical tube.

Last night I just had it on a bracket clamped in my dovetail:
Attachment:
polecam2.jpg
polecam2.jpg [ 245.17 KiB | Viewed 1095 times ]


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