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Stargazing Saturn using ETX-105 and a QuickCam 4000

  1. Nov 26, 2004 #1

    russ_watters

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    I posted my own thread without even seeing this one. D'oh. Anyway, I got my best yet (only my 3rd try...) shot of Saturn. The sky was very clear, but it was windy, full moon, and a lot of light pollution. I had to wait for a break in the wind, then shot a 30 second avi clip. Equipment is an ETX-105 and a QuickCam 4000. Photo taken at prime focus (1470mm), about 300 shots aligned, stacked, and processed with Registax.
     

    Attached Files:

  2. jcsd
  3. Nov 28, 2004 #2

    turbo

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    Gold Member

    Killer! Astrophotography is easy to do but hard to do right, and for your third attempt, that's pretty impressive.
     
  4. Nov 29, 2004 #3
    That's pretty awesome russ. I've been waiting for clear skies here for a while, but looks like this morning should be good. I'll try to get one of Saturn.

    I'm not very good with registax. Do you have any tips, Russ?
     
  5. Nov 29, 2004 #4

    russ_watters

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    Well, when you say you're not very good, what do you mean? Anyway, I'll tell you what I know:

    The webcam setup is key: the gain should be all the way down if possible - having it up at all just adds noise. The shutter speed should be as fast as possible while still being able to see the image. That'll leave you with a very, very dim image. That's fine - fast shutter speed means less atmospheric distortion and stacking the images makes them brighter (essentially, stacking increases signal to noise ratio, ie contrast). Also, if the image is too bright, you'll end up washing out all the details. Attached is a still from that Saturn video. Its unedited - just cropped. The video is uncompressed avi at 4 fps (I made the mistake of trying 15 fps with a .2s shutter speed :uhh: ). With the wavelet processing, the first 4 layers are what I generally use, in a bell curve (most of the detail is in the 2nd and 3rd layer). Don't overprocess (you'll know).

    Last night, I tried Jupiter - I stayed up until 4:00 to get it. Attached is all I could do with stacking/processing. The Jupiter and Saturn pics are both of the same magnification (about 230x). Jupiter was shot at about 13 degrees above the horizon, Saturn about 70 (I took some more shots last night with similar results). Obviously, its utterly useless to try to image something so close to the horizon (I'm working on an atmospheric model in Excel to calculate just how much atmosphere you look through at various angles). I may try Jupiter again next week when it is eclipsed by the moon - it'll be a little higher then.

    I know its obvious, but focus is critical and can be tough, especially if the atmosphere is bad or the image is dark. Up the brightness temporarily (but don't wash out the pic) to get it bright enough to focus or focus on a brighter (or higher, where the atmosphere is more stable) object.

    I haven't had any luck with Saturn in a Barlow lens - my telescope doesn't pull in enough light to make it bright enough to image. Maybe Jupiter when it gets higher/closer. I'm not too worried about that though, because with a 2x barlow lens, I'll get about 460x magnification (calculated from the image size on the computer screen), which is above the theoretical max of my scope anyway (about 350x).

    I have yet to have any success at all imaging deep-sky objects. The magnification at prime focus is far too high and I'm not having much success getting my focal reducer to work (it doesn't fit the telescope and I'm trying to adapt it).
     

    Attached Files:

    Last edited: Nov 29, 2004
  6. Nov 29, 2004 #5
    Thanks russ.
    I just meant I could never get really good results with registax, but now I think it's because I had the shutter too slow so the image was too bright to work with before stacking. I'll try it out tonight with a faster shutter.
     
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