Somthing a little different

Discussion in 'General Gallery' started by pursuer, Apr 2, 2005.

  1. pursuer

    pursuer TPF Noob!

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    There isn't a lot of astrophotography on this forum for obvious reasons and this certainly isn't one of the best examples around but I thought I would share it anyway.

    This is an image of the orion nebula that I took a couple of months ago but just completely reprocessed it today.

    It is the result of 6X30 second exposures and 1 10 second exposure.
    combinded and post processed with Registar, MaximDL, PixInsight and photoshop CS.

    [​IMG]
    Thanks for looking, hope you enjoyed.
     
  2. Meysha

    Meysha still being picky Vicky

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    Wow!! ( I seem to be saying that a lot on this forum!)
    I have no clue what-so-ever about Astrophotography,, but that's so puurty. It's gorgeous!

    Is the nebula really that colour in real life or did you colour it in PS?
    If it's really that colour.. then.. WOW! If you coloured it yourself.. then WOW great PS work!
     
  3. pursuer

    pursuer TPF Noob!

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    Thanks, I didn't color it, just a slight saturation boost and some level adjustment but the colors are clearly visiable in the raw image. Im glad you like it :).
     
  4. art tesian

    art tesian TPF Noob!

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    That is a great photo.Is it possible to give a quick run down on how and what you used? Very nice.
     
  5. JonMikal

    JonMikal TPF Noob!

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    awesome shot - i like it! :thumbup:
     
  6. dalebe

    dalebe TPF Noob!

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    nice shot great colours, does'nt look real, i do'nt know anything about astrophotography either but this sure looks good to me.
     
  7. pursuer

    pursuer TPF Noob!

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    Sure, I used a canon 300D at prime focus with a 10" diameter reflecting telescope. Thats basically like haveing a 1200mm prime lens. The telescope was mounted on an EQ-6 equitorial mount which slowly turns to compensate for the earth's rotation keeping the nebula centered in the frame. The tracking allows for long exposures. The longer the exposure the more detail and color is recorded. The length of the exposure is limited by how precisely the mount is aligned with the celestial north pole and the quality of the drive.
    Precise polar alignment is very time consuming so I just did a rough alignment and stacked short 30 second exposures at ISO 800. Once I had the exposures I put the dust cap on the telescope and took a couple of dark frames, basically a picture of the hot pixels and noise generated by the sensor.

    Once I was back inside I used PS to combine the dark frames into a master and then subtracted it from the normal exposures to help reduce the noise generated at ISO 800. next I used a program called regiStar to register or align all the images with each other. Then back to PS to combine the images by inverting and multiplying using the the source image as a mask. I now had a single image that I level adjusted and sent to an app called pixInsight for a three step noise reduction, then to MaximDL for a logarithmic histogram stretch then finally back to PS where I used a layer mask to merge the image with a shorter 10 second exposure for the central area, then a final level tweak. All pretty standerd for astrophotography.


    It's definatly real, you can see it with binoculars if you know where to look ;)
    I posted it because it is pretty, but for an astrophoto it has some problems, soft focus, bad tracking (misshapen stars) , it isn't framed very well but most of all it needs more overall exposure time. Still, this is the best astrophoto I have ever taken.

    If you have managed to read this far congratultaions on still being awake, that was a little longer windded then I planned, lol.
     
  8. LaFoto

    LaFoto Just Corinna in real life Staff Member Supporting Member

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    No matter if this one does not go with all the "rules for astrophotography": it is a fascinating photo, all the same!!! I love to be presented a "look into space", since I hardly ever get one myself (hardly ever? NEVER!), so I really appreciate these photos.

    Do I understand you right: this is a composition of 6 different exposures? Oh my, so much work put in just one photo!

    Worth the while, though. Very worth the while.
    Thank you so much for sharing!
     
  9. John E.

    John E. TPF Noob!

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    I have lots of shots from nasa stored for wall paper. I enjoyed looking at your picture and more so with your explaination. Very good and please continue to post these types of pictures, space is just so fascinating.
     
  10. pursuer

    pursuer TPF Noob!

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    Thanks guys, I will be sure to post more when I get a chance to get some, the weather hasn't been cooperating lately.

    LaPhoto you understand correctly. When photographing something this faint there isn't much difference between taking one long exposure or stacking short ones, they both boost the signal to noise ratio. Some of the really spectacular examples I have seen have had around an hour total exposure time spread out over many exposures.
    It is a lot of work but the processing is half the fun with astrophotography.
     
  11. Meysha

    Meysha still being picky Vicky

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    Does that mean you get less noise if you take a lot of short shots, than if you just took one really long shot?
     
  12. pursuer

    pursuer TPF Noob!

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    No it dosen't make a difference, the longer the total exposure time is the less noise there is. the advantage of taking multiple short exposures is it negates any trailing that might show up in a longer exposure due to imprecise polar alignment of the mount. Any drift as it is called becomes quite apparent at such a high focal length.
     

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