Are colors in astro photos 'real'?

In summary: Understand that the colors in space photographs are often artificially enhanced with digital post processing. However, some effects are due to the optics of the telescope itself.In summary, the colors in space photographs are often real, but the exposure times are long, so you will never see them with your unaided eye.
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Cyberspace
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There are lots of amazing photographs of nebula around. The colors contribute greatly to their grandeur.
But if we were able to get near enough to a nebula to see it with the naked eye would it possesses the colors we see in published photographs taken by telescopes? Or are the colors in astro photos in some way artificial or exaggerated?

Similarly I note that some astro photos show effects similar to a photographers starlight filter - have these shafts of light been added for dramatic effect in digital post-processing (eg photoshop) or are they genuine artifacts, eg of the telescope optics?
 
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Cyberspace said:
There are lots of amazing photographs of nebula around. The colors contribute greatly to their grandeur.
But if we were able to get near enough to a nebula to see it with the naked eye would it possesses the colors we see in published photographs taken by telescopes? Or are the colors in astro photos in some way artificial or exaggerated?
This depends greatly on the photo you're looking at, but in general the colours tend to be real - in the sense that they're not artificially added or altered (but not always, specifically in case of photos made in non-visible light, where the input has to be translated into visible output).
However, the exposure times are long, which means that you'll never see with a human eye the colours that you see on the photos. There's just not enough light reaching your unaided eye to activate the colour-sensitive cones, even when standing smack in the middle of a galaxy - best you can see of the Milky Way is a fuzzy grey band (its grey because rods in the eye are more sensitive to light, but perceive everything in the shades of grey).

Cyberspace said:
Similarly I note that some astro photos show effects similar to a photographers starlight filter - have these shafts of light been added for dramatic effect in digital post-processing (eg photoshop) or are they genuine artifacts, eg of the telescope optics?
Those are diffraction spikes due to telescope construction. Mostly caused by the struts holding the secondary mirror in e.g. Newtonian-type telescopes.
 
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The short is yes, the long answer is sort of. Here is an explanation: http://hubblesite.org/gallery/behind_the_pictures/meaning_of_color/
 
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Bandersnatch - thanks for that very informative reply, answered my questions perfectly.
newjerseyrunner - thanks for the link, very useful too.

Cheers
 
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There was a long thread on exactly that some time back if you feel like a forum search
 
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Cyberspace said:
There are lots of amazing photographs of nebula around. The colors contribute greatly to their grandeur.
But if we were able to get near enough to a nebula to see it with the naked eye would it possesses the colors we see in published photographs taken by telescopes? Or are the colors in astro photos in some way artificial or exaggerated?

If they are board spectrum visible light images, then they are likely true colour
eg this photo of the great Orion Nebula of mine ...

upload_2016-8-21_18-7-18.png
narrow band imaging in various wavelengths tend to be false colour eg this IR image of the Orion Nebula ...

m42-43_2m.jpg
Dave
 
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It's generally a good idea to inform yourself about the whole range of the electromagnetic spectrum that telescopes can capture, which is much wider than what a human eye can see. Anything above or below the range of visible light wavelength (400-780 nanometres) is invisible to the naked eye.

Many space photographs employ false colors in IR or UV photos. We wouldn't be able to see those objects through the naked eye.

It's also important to take into account how many light/years they are away from us. Today, the furthest ones don't look like the light that reaches us or don't exist anymore.
 
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davenn said:
this photo of the great Orion Nebula of mine ...
:thumbup::smile: How many stacks is this image made from ?
 
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For one of my favorite photos I added the diffraction spikes by adding wires across the front of my scope (which doesn't have struts). It is basically a natural color image (I used hydrogen alpha for red).

Horsehead-HaRGB.jpg
 
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1oldman2 said:
:thumbup::smile: How many stacks is this image made from ?

15 from memory
 
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russ_watters said:
For one of my favorite photos I added the diffraction spikes by adding wires across the front of my scope (which doesn't have struts). It is basically a natural color image (I used hydrogen alpha for red).

sweet shot, Russ ... I have imaged that region but not as well as you
 
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1. Are the colors in astro photos accurate representations of what we would see with our own eyes?

No, the colors in astro photos are not 100% accurate representations of what we would see with our own eyes. In most cases, these photos are taken using specialized filters, cameras, and techniques that capture wavelengths of light that are not visible to the human eye. Additionally, the colors are often enhanced or adjusted in post-processing to bring out details and improve the overall aesthetics of the photo.

2. Why do some astro photos have colors that are not visible to the human eye?

Some astro photos have colors that are not visible to the human eye because they are taken using specialized cameras and filters that capture wavelengths of light that our eyes cannot see. These filters allow astronomers to study different types of light, such as infrared and ultraviolet, which can provide valuable information about celestial objects that would otherwise be invisible to us.

3. Can we trust the colors in astro photos to be accurate?

Yes and no. While the colors in astro photos are not always 100% accurate representations of what we would see with our own eyes, they are based on real data and are not simply made up. Astronomers use advanced techniques to calibrate and colorize the images, and the colors can provide valuable information about the composition and temperature of the objects being photographed.

4. How do scientists determine the colors in astro photos?

Scientists determine the colors in astro photos through a process called color mapping. This involves assigning a specific color to represent a specific wavelength of light. For example, red may represent infrared light, while blue may represent ultraviolet light. They also use data from different filters and combine them to create a full-color image.

5. Can we see the colors in astro photos with a regular telescope?

In most cases, no. Regular telescopes are limited to the wavelengths of light that are visible to the human eye, so we cannot see the same colors that appear in astro photos. However, some objects, such as bright nebulas, may appear slightly colored with a regular telescope due to the natural color of the gases and dust that make up the object.

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