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  1. #41
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    Well I'm not seeing the files in the dropbox....

    They uploaded successfully but I have no clue where they went :/

    They should be under the dropbox parent directory, let me know if you can see them.
    Dave
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  2. #42
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    Dave,

    I can't seem to find them anywhere.

    Allan

  3. #43
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    Allan,

    I'm uploading them to another file hosting site, I'll post the link once they complete.
    Dave
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  4. #44
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    File #1, unprocessed stack of 13 images calibrated and integrated in PI.
    MEGAUPLOAD - The leading online storage and file delivery service

    File #2, processed stack of 30 images uncalibrated and integrated in PI.
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    File #3, unprocessed stack of 30 images uncalibrated and integrated in PI, used to create the processed image above.
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  5. #45
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    Dave,

    Got your images, thanks. Had a go at them and here is what I found so far...

    1)Your 30 stacked and processed:


    2)I adjusted the black level slightly to give a better background and punched the vibrance a little(IMO):


    3)Here is the 13 stack you sent raw and I processed:


    4)And here is my single processed image:


    Now there is no doubt your images have a little better nebulosity than my single, and I absolutely like your stars better from the standpoint that they are dimmer and detract less from the nebula (would love to know how you did that BTW), but I am still not seeing a massive difference.

    What do you think?

    Allan

  6. #46
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    I thought my image might be a little too bright and your version with a darker background is definitely better imo.

    I am still surprised with how good a single frame looks when processed, the background appears to have more chrominance noise but the detail showing is still impressive. Maybe 8min is enough for this target to get a reasonable result. I still believe that more integration time is better, however, it has diminishing returns since SNR increases by the square root of integration time (this is also true for a single long exposure).

    To reduce the size and intensity of the stars I created a star mask which was white wherever there was a star and black everywhere else. Wherever the mask is white a (any) process would be applied, and wherever there is black the mask protects that area. The tool used was an erosion filter (minimum filter) which then reduces the size of only the stars when applied through the mask.

    Here are a few examples using PI and PS:
    Star size reduction via Morphological Transformations | Deep Sky Colors - Astrophotography by Rogelio Bernal Andreo

    Reducing* Star* Bloat* in RGB* Images

    Reducing Star Bloat
    Dave
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  7. #47
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    Dave,

    Thanks! I will have a look at those. I really appreciate all your help with this, at least I don't feel like I have lost my mind anymore :-)

    Allan

  8. #48
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    Happy to help where I can
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  9. #49
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    So I was wrong when I said that stacking also increases the signal, it only decreases noise and that is what increases the SNR.
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  10. #50
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    So basically if you have no noise (I know, no such thing, just talking theory here) there is no advantage to stacking over a single shot.

    That is interesting, will have to put that to the test next time I get a chance.

    Allan

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