Pictures of M27 distinctly show the "bow-tie" section, the brightest part, as greenish, while the outer section of the long oval show red. This is exactly what I see in large scopes.
So the example you give of opposite color perception, while it may be true, doesn't apply to this object.
Ditto on M42, where photos show exactly the same colors I see visually and in exactly the same places.
And if size of image is a requirement of color perception, as, it is argued, is the faint image visibility, then I can understand the theory of perception.
Just one problem: I have looked through, nearly simultaneously, scopes of two sizes at exactly the same magnification, where the image sizes were identical. The larger scope showed a brighter image, more color, and an improved contrast enabling the visibility of fainter features.
What was different, of course, was exit pupil, since the two different scopes had different f/ratios. Obviously exit pupil plays a role in determining visibility of color, and object extension.
I play the devil's advocate, here, because I enjoy the conversation and I have read extensively on this subject, but why do all the theories of vision, related to the visibility of objects in a telescope, ignore the physical number of photons gathered by the larger aperture? Why isn't the image of an extended object simply easier to see in the larger scope because the larger scope gathers more light? Raise the intensity of the light level, and we all see more and better.
The Moon is bright in a small scope, but it is a LOT brighter in a big scope. At double the power of a scope 1/2 the size, the brightness per unit area calculates to be the same. Yet, the image is brighter. Period. It's easy to calculate why a stellar point is brighter, but not so easy to understand why an extended object like the Moon is brighter. The size of the image is not the explanation that works. Image intensity is simply higher.
Sometimes I think that people who argue about this resemble the old story about the argument about how many teeth are in a horse's mouth. Simply looking through telescopes of various sizes will convince you that the images are brighter, more colorful, and display more contrast in larger scopes.
An image intensifying eyepiece, like the Collins I3 will show more details in a larger scope. Why? Because there are more photons available at the source. Our eyes respond to photons. We see the images as brighter in bigger scopes because there are more photons and because the contrast delta has been stretched.
Maybe.
-------------------- Don Pensack
12.5" Truss Dob, 5" Maksutov
Sustaining Lifetime IDA member, TeleVue junkie
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Re: Is it possible to see the nebula with colour?
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