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 Post subject: Two telescopes in series?
PostPosted: Tue Dec 31, 2013 7:34 pm 
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Joined: Mon Oct 12, 2009 6:47 pm
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Location: Bolton
I think that last night I managed my best-ever polar alignment with a free-standing tripod-mount (CG5-AGT). I'd just plonked it down onto the lawn roughly aligned with Polaris, but when I looked through the polar-scope it only needed a tiny adjustment of the altitude screw to be "in the bubble".

I started off using my new StarWave 80ED fitted on it (it looks like this 'scope could be lucky, as this is the fourth time I've had it in action in the 12 nights since I got it?), to do some spectroscopy tests with our StarAnalyser filter and monochrome LX-webcam.

But in the meantime I'd noticed that Jupiter had emerged from behind the tall trees to the East of me; so once I'd got my spectra, I put the refractor back in its case and fitted my 8" SCT onto the mount in its place. As I'd not originally intended to do any planetary imaging, I hadn't put the 'scope outside to cool for an hour before starting, so my first images (using my Barlow-lens projector and a colour webcam) were quite wobbly. But they were still clear enough to show that a transit of Io was in progress: I could see the dark shadow cast by this moon on the top of the Jovian clouds. But then an old friend called to see me, so I couldn't stay outside with the 'scope, and so only managed to collect four sets of video files for stacking. But this is where my successful polar alignment became apparent - each time I popped out to the 'scope, the planet was still in the webcam's field-of-view (less than 200 arc-sec across), so I didn't need to spend any time with my flip-mirror re-centring it. 8-)
Attachment:
File comment: Animation of my four images, taken over the course of 86 miniutes. Each one is formed by stacking sequences of 300 individual images using RegiStax6, and then I used IRIS to align the four resulting images and unFREEz to animate them.
jupiter_30Dec13.gif
jupiter_30Dec13.gif [ 130.7 KiB | Viewed 4022 times ]

A happy New Year to all our readers, and here's hoping for many more clear nights than we managed in 2013...


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 Post subject: Re: Two telescopes in series?
PostPosted: Wed Jan 01, 2014 9:14 am 
nice capture Ross...


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 Post subject: Re: Two telescopes in series?
PostPosted: Thu Jan 02, 2014 9:54 pm 
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Joined: Fri Sep 07, 2012 7:20 am
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Location: Atherton
My attempts at Jupiter on Monday night weren't anything like you produced Ros. I could see some of the bands with a 24 eyepiece but nothing like the detail you achieved. I put the DSLR back on with a 2x barlow and light pollution filter and took a series of shots reducing the exposure to cut out the glare. I didn't think of trying video but the image was quite small anyway.

I first set up to resolve the tracking problem I've had. I put the EOS 7D straight onto the mount with a 200 mm lens and a filter and took several shots of the Pleiades at 3 minutes exposure. Perfectly round stars. (at last!!} Not quite in perfect focus but ROUND.It's a small step forward.
Bill


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 Post subject: Re: Two telescopes in series?
PostPosted: Fri Jan 03, 2014 10:08 am 
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Joined: Mon Oct 12, 2009 8:27 pm
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Location: Adlington
Bill,
Good to hear you have round stars at last - every imager's dream.

For focusing I set the lens wide open with live view 10x on a bright star - then stop down for the images. I recall you have the filter at the front stopping the lens down - it will be easier if that is removed just for focusing. Also front filters can produce reflections that look like comets so Comet Kos might make another appearance!


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 Post subject: Re: Two telescopes in series?
PostPosted: Fri Jan 03, 2014 11:17 am 
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Joined: Fri Sep 07, 2012 7:20 am
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Location: Atherton
Thanks Dave. I did think of making a small bahtinov mask but I'll try your approach first.


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 Post subject: Re: Two telescopes in series?
PostPosted: Fri Jan 03, 2014 10:45 pm 
:roll:


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