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Stargazer33

Help needed with webcam imaging of DSOs!

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Hi, can I please ask for some help/advice on imaging DSOs with a webcam and laptop?

Last night was the first night for quite a while that I have been able to get out and use my new 'scope.

I used it about a month ago to look at the Ring Nebula (M57), Dumbell Nebula (M27), The Great Globular Cluster (M13) in Hercules amongst others and was waiting for the chance to do some imaging.

Well, last night I got my chance and set the 'scope up, let it cool down, did an alignment with an additional 3 calibration stars. I then got the mount to swing to M57, got it right in the middle of the eyepiece and then swapped to the webcam (Philips SPC900NC) and...nothing. I tried again and again swapping between the eyepiece and the webcam, adjusting the focus, changing the gain, exposure, brightness and the other one which I can't remember at the moment and...nothing.

I even focused the webcam on Vega and then swung to M57 so I at least knew that the focus should be right, but then I couldn't tell if the 'scope had swung dead on to the nebula!

PLEASE...what am I doing wrong? Or am I just expecting too much from my set-up. Will I never see a DSO on a laptop screen due to their low light levels? If that is the case how do you know that you have got your subject in view?

It was really frustrating and probably caused me to pack up sooner than I would otherwise have done as it was reasonably good seeing and nice and warm with no dew build up.

Any comments, suggestions would be greatly appreciated as I am intending on going out again tonight.

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A normal webcam doesn't have the sensitivety to capture feint DSOs. You need a camera that is capable of longer exposures and works at low light levels. The SPC900 can be modified to allow exposures of a few seconds (check the diy section or google Toucam LX mod).

Peter

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What settings were you using on the webcam?

Just video?

If so, then you won't. You need long exposure to be able to pick up the gas and nebulosity.

must type faster!!

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Thanks for the replies guys...hey i'm a...ahem, sorry!

I thought stacking loads of single frames in Registax would make up for the feint image in each frame.

I can see how a long exposure mod will help with the imaging but how does that help with lining up the DSO on the laptop screen? The 'live' view from the webcam will still be the same real time image, won't it?

Bryan

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You have to take a long exposure to get the framing correct, too.

Stacking lots of frames doesn't increase the amount of signal over a single frame. What it does is reduce the amount of noise in the image. To get more data you need to have longer exposures.

James

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So...you don't actually get a 'live' view on the capture programmes preview screen? You just take a long exposure frame and look at that frame and then move the 'scope' a bit (hopefully in the right direction) and take another frame and view that... and so on and so forth, until you get the framing that you like?

This is then where you build up your darks, biases and flats and stack them all together.

This is definitely not a point and shoot sort of game is it!

Thanks, looks like I may have to look around for another camera to mod - or invest in a DSLR!

Bryan

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....This is definitely not a point and shoot sort of game is it!....

SOOOOO true. You have learnt the first rule of astro imaging!

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You do *NOT* talk about astro imaging!

Or was that something else?

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So...you don't actually get a 'live' view on the capture programmes preview screen? You just take a long exposure frame and look at that frame and then move the 'scope' a bit (hopefully in the right direction) and take another frame and view that... and so on and so forth, until you get the framing that you like?

This is then where you build up your darks, biases and flats and stack them all together.

This is definitely not a point and shoot sort of game is it!

That's about the long and the, err, long of it, really. There are other ways you can handle the framing if you know what stars you're seeing on the screen as they'll probably be brighter than anything else, but there are not many short cuts that I'm aware of.

James

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Thanks for all the help!

I think I am getting there now. Not sure whether to get the soldering iron out or to wait a bit and get myself a secondhand 450D.

Now...what did I do with that lottery ticket?...

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