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Rosette Nebula

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  • Rosette Nebula

    Rosette Nebula, a giant molecular cloud in the Monoceros region of the Milky Way Galaxy.
    5,219 light-years from Earth, 2023​.

    Telescope: Esprit 100ED
    Camera: ZWO ASI 2600MC
    Mount: AM5
    Filter: Optolong L-Enhance narrowband

    80 subs, 180" each for a total integration time of 4 hours.
    Pre-processing and processing in Pixinsight. Post-processing in ACD Ultimate 2023.

    VIEW

  • #2
    Jerry Gerber

    Spectacular!

    Can you perhaps briefly explain "80 subs, 180" each for a total integration time of 4 hours".?

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    • #3
      Originally posted by Greyfox View Post
      Jerry Gerber

      Spectacular!

      Can you perhaps briefly explain "80 subs, 180" each for a total integration time of 4 hours".?
      Astrophotography is very different from other types of photography. The light from deep space objects is very faint, it requires multiple exposures of the same object. These exposures are called "subs", or sub-exposures, because they will be combined into one image to create better signal-to-noise ratio and to bring out faint details that one exposure (unless that one exposure were hours long) can't do. After taking the images, software is required to calibrate, align and integrate all of the images into one image.

      The total integration time is the total exposure time of all the subs combined. For example, in the above image I took 80 exposures, each exposure being 180 seconds, or 3 minutes long, for a total of 4 hours of exposures.

      During the exposure time the object is slowly moving across the sky, as the earth is rotating on its axis, so the stars and other objects in space appear to move from east to west. This is why a mount is required that can track the movement of the object. This is further helped through what's called "guiding" or "autoguiding"--using a small camera to follow very precisely the movement of a star (or multiple stars) and send very small corrections to the mount to ensure that the object remains in the field of view while the earth turns.


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      • #4
        Another spectacular photo, thanks for sharing!

        Thanks,
        Tristan H.
        ACD Systems

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        • #5
          Magnificent, thank you.

          Can one use their 35mm digital camera mounted to a telescope to acquire the same images?

          Thanks for your reply.

          John

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          • #6
            Originally posted by harpo View Post
            Magnificent, thank you.

            Can one use their 35mm digital camera mounted to a telescope to acquire the same images?

            Thanks for your reply.

            John
            I've seen quite a few excellent astro images taken with a full-frame digital camera, and I don't see any reason why 35mm can't be used. I've never done it so I can't say much about it. The issues of having to take long exposures, 3-10 minutes each, and take a lot of them, still pertains. So does having a solid mount that can track and guide accurately. I would guess there's differences in technique because digital sensors, particularly those on cameras designed specifically for astrophotography, acquire photons differently than film does. Best to join an astrophotography forum and ask around, you'll get better answers than I can give you.


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            • #7
              Thank you Jery Gerber for sharing this great photo and for the explanations provided during the shooting.
              Astrophotography has now a little less secrets for me.

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              • #8
                Magnificent !

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