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How realistic are the colors that we see in pictures of galaxies/nebulas?

  1. Nov 29, 2011 #1
    In pictures that we find of galaxies and nebulas there are usually very bright colors in them. For example, if you look at a picture of the horsehead nebula you typically see pink, purple, red, orange and blue. Are those a real representation of how the nebula would appear to the naked eye?

    Also, if they are a real representation of how we see them... would you still be able to see those colors if you were in the nebula itself?

    I know this is a wierd question but I'd appreciate it if I could get an answer.
     

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  3. Nov 30, 2011 #2
    Many astronomical photographs are enhanced to maximise the differences in colour, so as to bring out detail in greater clarity. When these are published in the general press, or even in popular science publications this enhancement is not always mentioned. Any such photographs in textbooks or journal articles will normally be so identified.
     
  4. Nov 30, 2011 #3

    Drakkith

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    Unfortunately, other than stars, almost all other astronomical objects would NOT look as they do in pictures with the naked eye. Especially as you get closer or within them. Many are so faint and so widespread that unless you are taking long exposure images you will not see the color and detail.
     
  5. Nov 30, 2011 #4
    Reflection nebula actually are blue and emission nebula are red, http://www.enif.com/horsehead.html [Broken] . Of course even if you were inside them you'd probably have to let your eyes get dark adapted. On the flip side, some instruments take images outside of the visible spectrum, and scientists have no choice but to convert them to a visible color.
     
    Last edited by a moderator: May 5, 2017
  6. Dec 2, 2011 #5

    russ_watters

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    Our eyes are not optimized to detect dim colors, so at the very leasr, astrophotos have more color saturation. Otherwise, some display real colors while others use special filters and map them to arbitrary colors.
     
  7. Dec 2, 2011 #6

    davenn

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    As Russ says ... our eyes are not particularly sensitive to colour.
    Try determining any colour of an object in dim lighting. Difficult to impossible.

    Many photo's do show true colour, just as many can be enhanced or even have false colours attributed to show temperature change or some other feature.

    I have done a lot of astro photography over the years and I can attest to the fact that many of those deep space objects like nebulae do have strong colours

    here's one example that a mate and I did some years back
    this is a 30 minute exposure on Kodak 400ASA film
    Prime focus 8", F5, 1000mm focal length Newtonian scope
    There is absolutely NO colour enhancement !!! this is as it is straight out of the camera

    attachment.php?attachmentid=35158&d=1304495278.jpg

    Dave
     
  8. Dec 2, 2011 #7

    turbo

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    As dave has explained, our eyes are not especially adapted to perceiving colors in low-light situations, and we see at best grays and greens in bright nebulae. If you can accept the color sensitivity of negative film or slide film as a "reference", there are lots of examples of "real" colors out there. When I was shooting astrophotos years back, I used Fuji film at first (for its enhanced red response) and later moved on to Konika because they had developed an ISO 3200 negative film without much more noticeable grain than Kodak or Fuji at 800/1600)
     
  9. Dec 6, 2011 #8
    Very nice Dave!!
     
  10. Dec 6, 2011 #9
    Unfortunately, there is no such thing as a true-color Hubble image. All Hubble images are actually black and white, then the individual elements in each shot are each assigned their own color.
     
  11. Dec 7, 2011 #10

    Drakkith

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    This is as true as saying a color digital camera is not true color. The photo detectors used are ALL monochromatic no matter what device it's placed in. Color cameras have small filters of red, green, or blue over each individual pixel and then combine them digitally to make a color photo. You eye works almost the same way when gathering light.
     
  12. Dec 7, 2011 #11
  13. Dec 10, 2011 #12
    They also take seperate pictures of normal, infrared, ultraviolet, xray, and radio. Then all the pictures are combined on top of each other to make extraordinary colorful pictures to make it more dramatic.
     
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