Starry Sky Animator

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Offline Davo

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    Starry Sky Animator
    « on: 02 / October / 2013, 06:21:17 »
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    I just did my first overnight run with my new C# capture app and you can see the video here

    Not a valid vimeo URL
    What I did was use mweerden's CHDKPTPRemote.NET and chakphanu's branch of it to give me LiveView and remote camera control. I then added ASCOM support for telescope control.

    The app works by taking a long exposure while the scope tracks the stars. It then returns and points to the original start point and takes another tracked shot and so on. This means that there are no star trails but the animation looks like it is viewing a fixed part of the sky. The 21 second exposure shows a lot of very faint stars. You can also see a meteor at 2.12UT and a satellite flare? at 4.35UT.

    Many thanks to mweerden and chakphanu for a brilliant piece of code.

    I am hoping to use it to capture comet Ison which should be visible come November.

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    Offline lapser

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    Re: Starry Sky Animator
    « Reply #1 on: 02 / October / 2013, 14:31:45 »
    Wow, that's really impressive! Was this technique your idea, or has anyone done this before?

    I've played around a little with night time lapses with the G1X and SX50, but I don't have an equatorial mount., and yours is way out of my price range.

    One thing I've learned is that it's hard to see a meteor or other flash that appears in a single frame of a video at 30fps (or 25 fps, I assume). Sometimes you see it, and sometimes you don't. At 15 fps, you can reliably see it, but that slows down the video by half, and makes fast moving elements, like clouds choppy. My solution is to repeat the frame with the meteor in it a few times, or hold it for a second or two. I used the hold technique in this video:

    http://www.youtube.com/watch?v=Ap38PBGcSX8#

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    Re: Starry Sky Animator
    « Reply #2 on: 02 / October / 2013, 14:51:40 »
    .... but I don't have an equatorial mount., and yours is way out of my price range.

    http://www.astropix.com/BGDA/SAMPLE2/SAMPLE2.HTM

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    Offline lapser

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    Re: Starry Sky Animator
    « Reply #3 on: 02 / October / 2013, 16:09:26 »
    http://www.astropix.com/BGDA/SAMPLE2/SAMPLE2.HTM
    Thanks for the link. I've considering building a barn door contraption, but I'd like to have something motorized, and less work to build. I'm thinking of getting the Orion EQ1 setup, for about $150:

    http://www.amazon.com/gp/product/B0000XMX8O
    http://www.amazon.com/gp/product/B0000XMWBW

    It would take some serious hardware hacking to get it to work with an external controller.

    I sure wish there was a good way to send a signal FROM the camera, instead of just the camera sensing external usb power on and off. I wonder if it would be possible to turn the power off and on to the HDMI output connector somehow? Has that been looked at?


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    Re: Starry Sky Animator
    « Reply #4 on: 02 / October / 2013, 16:20:45 »
    I sure wish there was a good way to send a signal FROM the camera, instead of just the camera sensing external usb power on and off.
    A phototransistor attached to one of the camera LED's with chewing gum or something else sticky seems to be the method of choice.

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    Offline blackhole

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    Re: Starry Sky Animator
    « Reply #5 on: 02 / October / 2013, 16:27:52 »
    Quote
    I just did my first overnight run with my new C# capture app and you can see the video here
    Good job!
    Did you tried to shoot a DSO through telescope on the heq5 with a810?

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    Offline Davo

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    Re: Starry Sky Animator
    « Reply #6 on: 03 / October / 2013, 07:02:16 »
    Wow, that's really impressive! Was this technique your idea, or has anyone done this before?

    I've played around a little with night time lapses with the G1X and SX50, but I don't have an equatorial mount., and yours is way out of my price range.

    One thing I've learned is that it's hard to see a meteor or other flash that appears in a single frame of a video at 30fps (or 25 fps, I assume). Sometimes you see it, and sometimes you don't. At 15 fps, you can reliably see it, but that slows down the video by half, and makes fast moving elements, like clouds choppy. My solution is to repeat the frame with the meteor in it a few times, or hold it for a second or two. I used the hold technique in this video:

    http://www.youtube.com/watch?v=Ap38PBGcSX8#

    The idea just came to me recently but I am sure it has been done before. Otherwise, you just watched the world's premiere  :)

    You should build yourself a DavoKam which is based on the old timer drive idea like this one.

    http://www.instructables.com/id/Standalone-mount-for-astro-photography/

    Use a stepper motor instead of the timer and control it with a Raspberry Pi or Arduino. The controller will open the shutter and drive the motor at sidereal for the exposure duration (say 20s) and then close the shutter. It will then move the stepper quickly back to its start position and take the next shot and so on. You will end up with an image sequence like my video.

    Great tip re the meteors. I am going to rework the video to look more like yours.

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    Offline Davo

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    Re: Starry Sky Animator
    « Reply #7 on: 03 / October / 2013, 07:06:56 »
    Quote
    I just did my first overnight run with my new C# capture app and you can see the video here
    Good job!
    Did you tried to shoot a DSO through telescope on the heq5 with a810?

    Not yet but I saw a recent M57 on here that whetted my appetite. I was actually doing a drift align on my mount for this reason when I managed to damage it. Once I repair it I will definitely try a digiscoped CHDK DSO. My app is also configured to shoot normal long astro exposures and exposure sequences which will be a big help.


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    Re: Starry Sky Animator
    « Reply #8 on: 23 / October / 2013, 23:18:45 »
    http://www.astropix.com/BGDA/SAMPLE2/SAMPLE2.HTM
    Thanks for the link. I've considering building a barn door contraption, but I'd like to have something motorized, and less work to build. I'm thinking of getting the Orion EQ1 setup, for about $150:

    http://www.amazon.com/gp/product/B0000XMX8O
    http://www.amazon.com/gp/product/B0000XMWBW

    It would take some serious hardware hacking to get it to work with an external controller.

    I sure wish there was a good way to send a signal FROM the camera, instead of just the camera sensing external usb power on and off. I wonder if it would be possible to turn the power off and on to the HDMI output connector somehow? Has that been looked at?

    You can attach a motor to it. And it's just 2 boards with holes, a hinge and a bent threaded rod.

     

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