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Webcam for 200 dob

Celtic Deacon

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Celtic Deacon

Celtic Deacon

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A few months before I bought my scope I got rid of a spare webcam. Now I think I might want to have a go at imaging, after sticking a compact against the ep and finding results not too bad. What is the cheapest webcam you'd suggest that would be ok for me to start with?

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JamesF

JamesF

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An Xbox camera is about as cheap as you can get and might be ok after modding it to add a nosepiece and kill the on-board LEDs. A modded Lifecam Cinema seems to be one of the other favourites, but it'll be a fair bit more expensive. The Xbox cameras can be picked up from ebay for much cheapness.

James

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JamesF

JamesF

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!!! £4.95 and hours of work! Jigsaws would have been better!

Took me about half an hour to mod one camera. Perhaps an hour if I include removing the base etc.

If you want less work then you may be able to pick up an SPC880 or SPC900 on ebay for £50+.

Or if you want no work at all then there's something like the DFK21, starting at around £275.

James

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JamesF

JamesF

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Out of interest, what's the sensor size on the xbox cam & how adjustable is it wrt to exposure etc?

Sensor size is 640x480 pixels, or about 5mm x 4mm.

Exposure appears to be adjustable over a fairly wide range of values, though when I point mine out of the window during the day I have to have the exposure set very close to minimum. It also has auto-exposure though for astro use you'd almost certainly turn that off. There's no obvious scale for exposure as far as I can tell, so you can't, say, specifically set the exposure to one second. Gain, gamma and saturation can also be modified and there are other controls that you'd probably not bother with for astro use.

My biggest gripe with it is the image noise, but perhaps I've been spoilt by the SPC900.

James

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Tribal-Wolf

Tribal-Wolf

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I have just bought an xbox cam and modded it to fit in the scope but I am going to add a fan as they get hot really quickly so there is a lot of noise in the images. The Philips cam is still the daddy for now but they are holding their money, they seem to bring around £70 now but on the plus side you can always get your money back. They are also the best one to mod for long exposure which you need to image DSOs and anything dim. I'll keep you posted on the xbox cam cooling.

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JamesF

JamesF

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I've been thinking that the Xbox cam could probably do with some cooling myself. I did some tests taking a frame every ten seconds and even after a fairly short run there was a good deal more sensor noise on the last image than the first. Just having more space around the back of the sensor would probably help.

Not entirely sure about adding a fan due to the potential for vibration, but I'll be interested in what you come up with.

James

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JamesF

JamesF

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As a quick datapoint, I ran two Xbox cameras side-by-side this evening for some capture tests. I'd not bothered to replace the front casing on one of them and it was significantly less noisy. The average increase in pixel value on the camera without a front casing was less than half the increase on the camera with the casing replaced.

It's not exactly scientific, but it does make it look like some additional cooling may well be helpful.

James

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Tribal-Wolf

Tribal-Wolf

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Well the exhaust fan definitely worked. I let it run for 30 mins with high load and a dark background and there were no hot pixels. Need to try it in the scope as I'm not sure about the focus length until I do but there is too little vibration to make a difference and no image noise from the fan.

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post-32952-133877765326_thumb.jpg

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JamesF

JamesF

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Well the exhaust fan definitely worked. I let it run for 30 mins with high load and a dark background and there were no hot pixels. Need to try it in the scope as I'm not sure about the focus length until I do but there is too little vibration to make a difference and no image noise from the fan.

That's very neat indeed. Have you fed some 5v wiring up through the bottom of the webcam to power the fan, or is it driven off the USB power?

James

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Tribal-Wolf

Tribal-Wolf

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It's within the allowable current draw for the usb port or I would have gave it a separate supply. This it just a prototype anyway to see what the results are. I was thinking of putting a sensor in so the fan came on when needed. I have another cam and a more efficient fan coming but not worth doing much till I know how it copes. Weather is killing any chance of trying it for a few days.

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Tribal-Wolf

Tribal-Wolf

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Just noticed on this that the fan on the pic is a 12v, I ordered two and the other is definitely a 5v so I never checked lol and they must have sent one wrong fan which by chance I fitted. Good job it's cloudy tomorrow it looks like I have a job to finish lol.

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Stargazing_Cliff

Stargazing_Cliff

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Since seen your cam cooling mod i have made somet for mine :D cud not find small enuff fan so made cooling box mod instead.

will make better box or put some waterproof tape around cam and box.

I put old pentium 3 cpu fan inside box about quater into box gives enuff cooling using seperate powepack to run fan at moment testing process soon as skies clear been horrible for days now

stargazing_cliff-albums-cam-modifications-picture17111-xbox-cooler-mod-using-cpu-fan-made-box-around-fan-cut-away-back-xbox-cam-plastic-attached-fan-box-made.jpg

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