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PostPosted: Tue Oct 10, 2006 9:42 am 
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Joined: Tue Oct 10, 2006 9:35 am
Posts: 1
Hi:

I'm using my 10" dob, with a Toucam 840k for image-capture.

I've got some great shots of the moon, but try as I might, I cannot even get Jupiter in focus with the webcam - nothing! I've removed the lens from the cam and I'm using this with a homemade "focuser" and a Vixen 2X Barlow lens.

Can anyone with experience with this webcam give me some pointers as to settings I might want to make on my cam's setup (I'm currently using VRecord as the application).

I'm a newbie to astrophotography and this is driving me nuts :evil:

I live In Australia, btw.

Thx!


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PostPosted: Tue Oct 10, 2006 6:31 pm 
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Joined: Fri Dec 03, 2004 9:58 pm
Posts: 3556
Location: Wellingborough
Hi Shane, and welcome! 8)

If you get good in-focus images of the Moon, then you should be able to get images of Jupiter. One well-known problem with Newtonian telescopes is that the focuser won't rack inwards far enough to place the webcam CCD at the focal plane, but that doesn't seem to be happening in your case as you can focus the Moon.

I'm not quite sure from your description just exactly what the problem is. You describe the problem as not being able to focus Jupiter -"nothing", but I wonder from that, if you are really having difficulty getting Jupiter onto the CCD at all? The field of view of that CCD is tiny and at focal lengths of about 2.5metres (250mm f5 plus x2 barlow) might just about be large enough to fit half a dozen Jupiters across it. The Moon is big (about 30 Jupiters across) and bright, so it's fairly easy to see when it is close to the CCD field of view and then make the required corrections to centre it, but Jupiter is a lot harder.

I suggest taking the time to make sure that your finder is perfectly aligned with the view seen in the webcam. It is probably easier to use a distant terrestrial object for this unless your dob has a drive system, then maybe fine align on the Moon (use a prominent crater). Then next time you point at Jupiter, you should be able to see the planet on your monitor - maybe just at the edge of the view- but you can then adjust to centre. In my opinion though you will find it very difficult to get Jupiter centred and keep it there without some sort of drive system, but Good Luck anyway.

Another problem could be with your software. It's quite straightforward to image the Moon in "auto" mode - results are reasonable- but to image Jupiter with details visible on-disk will require you to take over camera control in "manual" mode. Otherwise, the auto setting just gives a bright, overexposed planet but will show the Galilean moons. In manual you will need to adjust gain and gamma settings as well as shutter speed and frames per second to get the best raw frames you can for stacking and processing. But image processing is another whole topic. Go get those avis first :)

Have a think and please feel free to ask again if I've not been very clear ,

ATB,

_________________
Brian
52.3N 0.6W
Wellingborough UK.

254mm LX90 on Superwedge, WO ZS66SD, Helios 102mm f5 on EQ1, Hunter 11x80, Pentax 10x50
ASI120MC Toucam Pros 740k/840k/900nc mono, Pentax K110D
Ro-Ro roof shed


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