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Orion Nebula - 01/05/2022

Discussion in 'Astrophotography and Imaging' started by Ed D, Jan 7, 2022.

Orion Nebula - 01/05/2022

Started by Ed D on Jan 7, 2022 at 1:37 PM

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  1. Ed D

    Ed D Well-Known Member

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    I did a series of images to test the range of ISO values and exposure times to zero in on the ideal settings for my equipment: Canon T3i unmodified camera, Celestron CG-4 mount with RA motor. Because I don't have guiding, my exposure time limit is 30 seconds. At greater than 30 seconds I start getting elongated stars in my images. I also found that my ideal settings are ISO 400 and ISO 800. Lower ISO values require too much exposure time, and higher values introduce image noise. This is a screen shot of the eight good images and the folders containing the experiment images:

    IMG_0310.jpg

    Just for fun, I decided to stack the eight test images: ISO 400 @ 15/20/25/30 sec and ISO 800 15/20/25/30 sec. I used RegiStax 6 to stack the images. The output image was in TIFF format. I used GIMP to adjust the contrast and intensity, and also to save them in JPEG format. This first image is very subtly processed, not much different than the output image:

    M42 2022 01-05 Reprocessed Subtle.jpg
    Orion Nebula 01-05-2022 lightly processed image

    I this next image I did more intense adjustment, bringing out a lot of the H-Alpha at the expense of blowing out the Trapezium:

    M42 2022 01-05 Reprocessed Blown Out.jpg
    Orion Nebula 01-05-2022 more processed image.

    I think I'm on to something here. It seems that by taking single frames at various ISO and exposure values and stacking them, I'm capturing a much greater variety of data than when I was taking many exposures at the same settings. The more processed image has good contrast and detail, and shows more features than I have been able to get so far.

    It's not time consuming at all to take a variety of single images at various settings. Likewise, it's not a big deal to stack a few images, eight in this case, and then do simple processing. I'm not sure which of these two images I like more, but I do like them both.

    Ed D
     
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  2. Ed D

    Ed D Well-Known Member

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    As I was proof-reading my post, I noticed a couple of things about the images I forgot to mention. First is the lack of bloated stars. In images taken during the past few days I have gotten light to heavily bloated stars. The second thing I noticed is the lack of hot pixels. In some of the individual exposures there are red and blue hot pixels that do not appear in the stacked output image.

    Ed D
     
  3. Orion25

    Orion25 Well-Known Member

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    Nice work, Ed. That's an interesting idea of stacking images at various settings. I like both images for different reasons. I love the subtlety of the first image with the Trapezium visible, and I also love the fabulous nebulosity apparent in the second image. I did another round of single exposures the other night. I may them in a day or so. Still couldn't quite replicate my 2020 image but came close.
     
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