Posted 10 February 2013 - 02:30 PM
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...
Posted 10 February 2013 - 02:53 PM
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.
Posted 10 February 2013 - 07:13 PM
(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.
Posted 12 February 2013 - 10:25 PM
Posted 12 February 2013 - 10:38 PM
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.
Posted 13 February 2013 - 12:21 AM
Posted 13 February 2013 - 02:57 PM
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.