Quote:
Originally Posted by MattyD
I was under the impression that it's our eyes that are the problem, and not necessarily the optics? You need a really long exposure regardless of the size of the telescope to get colour. Well that was my impression I could be wrong.
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What you are saying is correct the problem is with our eyes. We have two main types of photoreceptors called rods and cones. These cells are located in a layer at the back of the eye. Rods are used to see in very dim light and only show the world to us in black and white. The other type of photoreceptors, the cones, allow us to see colors. They are not as sensitive as the rods so they only work in bright light eg day time.
So to see colour you need to collect enough light from a celestal object to make it bright enough to tickle your colour receptors, so an aperture of about 20 to 30" may do it?
As to why celestial object look green in colour when using telescopes up to 12" plus some more, is because our Rods (night vision) operate at a wavelenght of +/-540nm this equates to the green part of the spectrum.
For further infromation follow the link
http://askabiologist.asu.edu/research/seecolor/