A&P Intro to image stacking: Step-by-step

Discussion in 'Lifestyle' started by ASIGN_Baz, Oct 7, 2009.

  1. ASIGN_Baz

    ASIGN_Baz New Member

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    Like a lot of astrophotographers, I get repeated questions on how to do things that although may seem simple, I have to remind myself that they were once beyond me...

    So last night, I sat up all night and stacked some images in Deep Sky Stacker, taking screenshots all the way and writing down what I did as I went.

    Hopefully this can answer a lot of questions and get the new blood in the game well on their way to adding to the richness of images proliferating amateur astronomy.

    http://www.asignobservatory.com/index.php?option=com_content&view=article&id=84&Itemid=125

    Have a crack, enjoy and let's see what you new folks can do!!! YEEEHHARRR!

    Baz.
     
  2. tetsuo

    tetsuo And shepherds we shall be...

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    :bowdown::bowdown::bowdown: i've been wanting to try to do some basic astrophotography and this tutorial should really help.
     
  3. free_notes

    free_notes New Member

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    i had no idea you were using specialized software. i thought it was all done in photoshop.

    anyway thanks for the guide. i've been wondering how your images were made.
     
  4. Mutombo

    Mutombo New Member

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    Wow awesome, this is great. I have far too much light pollution where I live, but next time I get out of the city I'll give this a try.
     
  5. Ty Webb

    Ty Webb You don't have to go to college. This isn't Russia

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    I can't wait to try this!!!!
     
  6. ericande

    ericande Active Member

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    Perfect, I'm going to spend this weekend in a pretty desolate area, perfect chance to try it.
     
  7. psykosis

    psykosis Go placidly amid the noise and the haste

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    It won't quit raining here, and the moon is rather full. Two weeks and I could knock one of these out though.
     
  8. Professor Chaos

    Professor Chaos New Member

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    Great edu. Can't wait to try this out :bigthumb:
     
  9. EWhytsell

    EWhytsell New Member

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    Some of the best images on cloudynights.com have come from a guy that lives in Manhattan. Last I read he uses a CCD, runs R,G,B color filters along with a hydrogen alpha filter and of course light pollution filters.

    Also some of the shots I get are shooting directly above a population area of 2 million.

    The real trouble with light pollution is that you can't see what your shooting at until you've processed the image in some cases. You just have to rely on your equipments guide computer to be on target.
     
  10. ericande

    ericande Active Member

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    What's the best ISO to shoot at? I found some recommendations for older Canon digital cameras that were around 800 so I'd assume 1600 with a Nikon D90?

    What's the optimal number of exposures? Is there much benefit past 10 or so?
     
  11. ASIGN_Baz

    ASIGN_Baz New Member

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    The more photos you take, the smoother and less noisy it becomes. There is obviously a point where the returns are less and less, but it is not unusual to stack 30 or more.

    Some of my subs from my CCD astrocamera are 20 minutes each, and I stack 20 or more of them to get a final image.

    With my DSLR CMOS chip, I am limited here in Canberra by light pollution to about 8 minute exposures whilst tracking through the telescope.

    When I shoot just camera on tripod out in the scrub, there is not much point going past 35 seconds at 18mm, or the stars just get too long and egg-shaped. The longer the focal length, the more it exacerbates the problem. Keep your focal length short, your aperture wide, and your exposures as short as is needed for this type of work.

    Depending on your F ratio, this should be between 20 and 35 seconds only.

    Go get 'em tiger!!!

    Baz.
     
  12. EWhytsell

    EWhytsell New Member

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    When shooting deep space objects people tend to use ISO 800-1600 (theres an ongoing debate which is better.) Really its sorta a mute point because noise isn't the main issue since we're shooting anywhere from 60 seconds to 8 minute shutter times. The more important factor is how much of the subjects data your actually recording vs the noise or just plain black sky. The brighter objects using ISO 800 isn't a bad idea, but I've seen no difference.

    The maximum number of frames before the advantage of stacking diminishes to a point that its not worth it is around 200 frames.
    I've personally never saw a reason to stack more than 80 frames because when I print my images they look great at that point.

    This information applies to DSLRS, CCD is different and many use really awesome cooling technology to get really long +20min exposures with lower noise than DSLRs.
     
  13. EWhytsell

    EWhytsell New Member

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    BTW I'd love to see what the newest Canon or Nikons could do to something faint like Horsehead Nebula. Currently it requires more than 6 min shutter time for me t pick it up in my 8" F/6.3 scope at ISO1600 so I'm thinking ISO 6400 could do the same job in 1.5 minutes. That would be very sweet.
     

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