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DIY all-sky cam?

msinclairinork

By msinclairinork
in DIY Astronomer

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yesyes

yesyes

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Hmmmm, not looking good...

I quickly knocked something together in Visual C# that switches the serial port RTS pin on and off at certain intervals.

Then I've started webcam preview in SharpCap.

While the long exposure is in progress the SPC900 sends black frames. Then I see one very bright frame (probably the frame containing the long exposure image). Then, when RTS is off, the camera transmits normal frames as if it was a normal webcam.

So I guess one needs to catch the next frame after stopping the exposure and throw away all other frames. I don't see how this would be possible with 2 separate applications without modifying the capture software.

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Gina

Gina

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Hmm... I see. So we need to collect all the incoming frames and process each individually, rejecting black or very dark ones. So, yes, it needs the capture software specially written it would seem.

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yesyes

yesyes

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Thanks. So the light cone at the sensor end of the lens must be quite wide and it is the sensor size of the SPC900 that limits the view angle to about 100-120 deg.

Still good enough to determine whether it is clear or not. But not really an all-sky camera.

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Horwig

Horwig

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My last post should have read "dome is on its way", but it might have made sense anyway. A thought has just struck me, any ideas on how much power it's going to take to keep such a large dome dew free?

Huw

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msinclairinork

msinclairinork

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hmm...your guess is as good as mine. But I was giving it some thought (could be way off here) and going by what I've used and seen.

I have a dew heater tape on my ED80 which I think draws around 0.5amp and works well.

Given the fact that the dome is well a dome that would probably mean more surface area to cover but the fact that it is acryilic rather than glass should mean it doesn't dew as easily and maybe even stay warmer? So I was thinking one of those dew heater tapes should suffice.

Could easily be way off the mark here...just brain storming. :)

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Horwig

Horwig

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Success!

Just set it up on the shed roof, bright sky to the east is the full moon rising. Not sure about the focus, and no anti-dew as yet.

Sky is perfectly clear, so will wait for clouds to give it a proper test, not that I expect to have long to wait.

Huw

post-19412-133877690902_thumb.jpg

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Gina

Gina

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Good result :eek: And nice job :p

So... it really needs a half inch sensor to get full coverage and a sensitive one to see stars but at least that lens seems to give virtually 180 degrees coverage and is a true fish-eye. I'm looking forward to having the time to investigate this myself but I think the cost of a suitable camera is going to be a problem. It will have to compete with my next scope :D

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yesyes

yesyes

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Finally some features on the sky that make it worth taking a screenshot of my sky cam. Attached is a screenshot from just now, about 4:45pm (it's already dark out)

So it does work with the SPC900 but it is nowhere near as wide-angle as I had hoped. So I rename it from all-sky-cam to sky-cam. ;)

I think it can still be used to check whether it is clear as a cheap solution. Haven't had a clear night yet to test with LX mode. Will post another screenshot once I have been able to try that.

post-14790-133877694006_thumb.jpg

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Reggie

Reggie

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I've had it in mind for ages to get a pan/tilt bracket system and a pair of servos and put an spc camera on it, you've got me wondering now if you could feed it wind/cloud direction data and have it keep a watchful eye on things? Yet another job for an arduino, small ps2 analog joystick on a pcb and you can be your own little ccctv operator (Closed Circuit Cloud Television, incase anyone thought the extra C was a typo ;))

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Reggie

Reggie

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I've got 4 webcams here to mess with, 1xspc900nc, 2x spc880nc and a trust thing. The trust thing may well end up being a cloud cam. once the camera is gutted from the case it should be sufficiently light weight to only need a micro servo I hope.

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ixalon

ixalon

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Thought for a moment that those were very strange sun spots! ;-)

Still waiting on the bits and bobs to build mine, but have been thinking about dew/snow protection (i.e. heating).

Using a USB camera, we've got a 5V supply and probably at most 400mA of current the controller can supply above what the camera needs (assuming the camera draws 100mA) to generate some heat. What's the most efficient device for converting this to heat? I know 2W isn't much, but I'd like to avoid running a 12V line alongside the USB if possible.

I've seen some people use old CPUs (e.g. USB Heater (or How to Upgrade Your Coffee Cup)), and the USB 'warmers' out there appear to use voltage regulators (e.g. LM117).

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yesyes

yesyes

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Using a USB camera, we've got a 5V supply and probably at most 400mA of current the controller can supply above what the camera needs (assuming the camera draws 100mA) to generate some heat. What's the most efficient device for converting this to heat? I know 2W isn't much, but I'd like to avoid running a 12V line alongside the USB if possible.

I've seen some people use old CPUs (e.g. USB Heater (or How to Upgrade Your Coffee Cup)), and the USB 'warmers' out there appear to use voltage regulators (e.g. LM117).

I've actually measured yesterday how much current the LX modded SPC900 draws. Here are the results:

http://stargazerslounge.com/diy-astronomer/148315-spc900-lxmod-yesyes-style-9.html#post2027811

That CPU heater is funny. But it's not the CPU that generates the heat but the 2 resistors underneath. I guess you could just put these 2 resistors (re-calculate to not draw more than 250mA) in the camera dome.

With mine I'll wait and see if dew becomes an issue...

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msinclairinork

msinclairinork

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I could also call it Light Pollution Camera

This is a 5 sec exposure of my clouded sky.

hmm...Perhaps we should of been thinking Narrow band!! ;)

Looking pretty good though their Chris. Yes not quite All-sky but I'd settle for that as you say - as a cheap option. And if a cheap bigger sensor ever comes along a quick swap I don't think would be to painful.

Looking forward to seeing the star test!

Thanks for sharing,

Michael

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