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#26 KerryR

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Posted 10 February 2013 - 02:30 PM

A fun thing to try with larger apertures, say 11"+, is to observe M42 against an early twighlight sky-- dusk or dawn, when the FOV has a distinct blue tint. To my eye, this made M42 distinctly yellow.

Otherwise, under normal (dark) observing, M42 is distincly blue-green to me, 35mm ep, 16" f4.5. Never a hint of reds.

Wouldn't we expect to see the pink tints in the brightest regions, the ones most likely to be bright enough to trigger cone cells? If memory serves, folks often report pinkish hues in the dimmer regions, which might suggest some artificial post-processing in the brain...

#27 Ebyl

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Posted 10 February 2013 - 02:53 PM

Well, color vision is technically an illusion. It's all "artificial post-processing" by the brain. It's an evolutionary trick that has provided us (and some other species) with an edge in survival.

Because our brains are constantly processing and doing comparisons, it's very easy for things to appear different than you might expect depending on the situation. In fact, our brains are often filling in the blanks from past experience, which isn't always accurate in the current situation.

Different color backgrounds will change the perceived color of an object sitting amidst that background. Numerous tests over the years have shown this.

#28 Gert K A

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Posted 10 February 2013 - 07:13 PM

If I understand how the eye work correctly a fully dark adapted eye looses the ability to distinguish colour.
(Or more precisely shifts toward blue "The Purkinje effect".)
See here Seeing Color
So if you got enough aperture to gather enough light to see, as in this example M42,
without being fully dark adapted you should have a greater chance of perceiving colour.

#29 mdalton

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Posted 12 February 2013 - 10:25 PM

I was looking at it last night with a Z12. I could see some pink for sure, and maybe a small amount green.

#30 Dave Mitsky

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Posted 12 February 2013 - 10:38 PM

The times that I have seen a ruddy color in the wings of M42 have been through large apertures on exceptional nights.

I was at the best "local" dark site last Saturday night. The conditions were good but not superb. While the views were very nice indeed, neither I nor the owners of 22 and 25" Dobs were able to see reddish hues in M42 that night at relatively low power. A blue-green hue surrounding the Trapezium was readily visible to me, however.

Dave Mitsky

#31 Dennis_S253

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Posted 13 February 2013 - 12:21 AM

A blue-green hue around the trap? That area was white as I recall and pure black to the east of the trap. Pale pink was ESE and WNW of the trap. There was another black area S of the trap, a big area surrounded by bright stars with one bright star SE. Most of the greenish-blue tint was N-W- and WSW and kinda took over the pale pink if I looked to long. Then the grey smoke took over the greenish-blue if I looked longer.

#32 Dave Mitsky

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Posted 13 February 2013 - 02:57 PM

Yes, that's right. The pale aquamarine color in the Huyghenian region that I noted was somewhat similar to that in Jeremy Perez's sketch at http://www.perezmedi...0011401_M42l...

The dark lane known as the Fish's Mouth (Sinus magnus) that protrudes into the Huyghenian region was black, of course.

At one point during the night, an SQM reading of 21.4 was taken, corresponding to a NELM of approximately magnitude 6.3.

During my very best views of M42 in the past, the area around the Trapezium appeared to be sky blue, the surrounding region green, and the sword and sail portions of the wings a brown to ruddy shade, all of which were pastel in nature.

Dave Mitsky






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