Another Witches Head Image

Discussion in 'Astro Photography' started by Mike Lewis, Jun 10, 2019.

  1. Mike Lewis

    Mike Lewis Staff Member
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    Here is a older image, shot with an astro modified DSLR (Canon T2i) using astro software that was able to bin the image 2x2. Binning reduces resolution while increasing sensitivity, often a fair trade when images faint objects. This also illustrates that even images of the same object can look different when taken with different equipment, under different conditions, at different locations, and with differing numbers of collected subframes.

    The Witches Head Nebula is a faint Reflection Nebula, whose natural color would be blue if not imaged here in B&W. In this case, binning a sensor with a Bayer color array necessitates only being able to reproduce the final image in B&W. In this case, the result is helped by the dark skies (Northern New Mexico) where this image was shot, increasing the overall contrast.


    Comments and crituques welcome.

    Here are the details on gear used and images collected to make this final frame:

    Equipment:
    Canon 550D (astro-modified, clear glass filter)
    Software Bisque MyT Mount
    Stellarvue SVQ100 Astrograph Refractor, 580mm @ f/5.8
    Unguided

    Software:
    Pixinsight Commercial Version 1.8
    Lightroom CC

    Light Frames:
    14 x 300 secs, binned 2x2 (1 hr 10 mins)
    2 x 240 secs (8 mins)
    Total 1 hr 18 mins

    Dark Frames:
    10 x 300 secs (50 mins)

    Additional Frames:
    Bias - 30
    No Flats
     
    AlanLichty likes this.
  2. Ben Egbert

    Ben Egbert Forum Helper
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    Nice job here, I like this.
     
  3. AlanLichty

    AlanLichty Moderator

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    I am continuing to learn from the techniques being used for astro shots like this. Very nice result.
     
  4. JimFox

    JimFox Moderator
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    Very cool Mike! Even without colors this looks amazing!

    I would crop some off the left to lose that bright star (?) along the lower left that is cut off. My eye gets drawn away from the Witches Head since that cut off star is so much brighter then the rest of the scene.
     
  5. Mike Lewis

    Mike Lewis Staff Member
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    Thanks everyone!

    Yes Jim, once again you're on to something. With astro in particular, you are frequently cropping due to some often unavoidable issues in the edges of the FOV. In this case I was probably so focused on that that I missed the issue you are mentioning. The star in question is Psi Eridani, a moderately bright ~4.8 magnitude star that can be a naked eye object under dark skies. The visibility of the nebula though owes itself to the MUCH brighter star Rigel, the brightest star in the constellation Orion, a blue supergiant that is approximately 47,000 times more luminous than our sun. It is outside of the FOV of this image (intentionally) to allow for the much fainter nebula to be captured. That blue light along with the natural tendency of dust to scatter the blue end of the spectrum, is what makes this nebula blue when seen in natural color (and the same phenomenon that makes our sky blue.)

    I do intend to get back to this target in the future and get a color version at some point, but it is a fascinating object and one of the more aptly named objects in the sky.

    ML
     
  6. JimFox

    JimFox Moderator
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    I hope you are able to get back to it. A color version sure would be cool!
     
    Mike Lewis likes this.
  7. Colorado CJ

    Colorado CJ Well-Known Member

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    Looks great Mike! Very detailed. When I tried the Witches Head with my DSLR, I really had to process the files to get anything out of it.
     
    Mike Lewis likes this.

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