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Observing star colours


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I have been reading "Viewing the constellations with binoculars" by Bojan Kambic.

The following is a quote from the book.

"For checking star charts while outside you should never use Red Light, even though this is

recomended by numerous writers. Orange and reddish stars will thus lose a lot of their hue

while the blue will be emphasized. It is wiser to use a normal but dim white light."

Does anyone agree or follow this advice.

Avtar

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Have read somewhere that said that a dim green light was better, and that would tie in with what you have highlighted above to a fair extent.

Green light would leave the Red and Blue sensory eye bits relatively unaffected.

Owing to the spectrum emitted by a star, Green is rare, think it would have to be caused by chemicals present and not purely by fusion light emission.

So dimming your response to Green would have the least effect on you distinguishing stars. Not many green stars, so if your response to them if lessened for a brief period you don't "lose" as many objects.

I assume that the idea of the artical you read is that a dim white simply diminishes the immediate response of the eye to everything more or less equally.

It is a difficult area as I find that red or white both cause me to lose night vision, not helped that if a person has a red head light on then it seems that as it is red it is fine to shine it in your face, because everyone says red is OK.

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Have read somewhere that said that a dim green light was better, and that would tie in with what you have highlighted above to a fair extent.

Green light would leave the Red and Blue sensory eye bits relatively unaffected.

Owing to the spectrum emitted by a star, Green is rare, think it would have to be caused by chemicals present and not purely by fusion light emission.

So dimming your response to Green would have the least effect on you distinguishing stars. Not many green stars, so if your response to them if lessened for a brief period you don't "lose" as many objects.

I assume that the idea of the artical you read is that a dim white simply diminishes the immediate response of the eye to everything more or less equally.

It is a difficult area as I find that red or white both cause me to lose night vision, not helped that if a person has a red head light on then it seems that as it is red it is fine to shine it in your face, because everyone says red is OK.

I'm no physicist, but that's what I couldn't work out, surely it's better to lose one colour slightly, than all?

I'll try the green instead though!

Just need to find some green sweet wrappers. :p

Cheers

Edited by bingevader
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Uranus is neat, really excellent disc at the moment.

You'll find differences in reported star colours not only due to different eyesights , but optical illusions.

For example a white star next to a red one appears white.

Nick.

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I have been reading "Viewing the constellations with binoculars" by Bojan Kambic.

The following is a quote from the book.

"For checking star charts while outside you should never use Red Light, even though this is

recomended by numerous writers. Orange and reddish stars will thus lose a lot of their hue

while the blue will be emphasized. It is wiser to use a normal but dim white light."

Does anyone agree or follow this advice.

Avtar

Hope this helps to clear things up. if you "skip to the end" the explanation for using red light essentially boils down to dark adapted vision of the rods, and their lack of response to light towards the longer wavelengths. http://hyperphysics.phy-astr.gsu.edu/hbase/vision/rodcone.html

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A number of big hitters argue in favour of green. However, will a low level red light really have much effect if you step up to the EP and get nicely re-adapted? For me the key thing is to use the lowest light level you can. Use the VERY badly illuminated charts as memory joggers but do your homework in the daytime.

Olly

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A number of big hitters argue in favour of green. However, will a low level red light really have much effect if you step up to the EP and get nicely re-adapted? For me the key thing is to use the lowest light level you can. Use the VERY badly illuminated charts as memory joggers but do your homework in the daytime.

Olly

A very good point. Well said.

D.C

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FWIIW there is a report study issued by the American Aviation Medical, on the effect of light on the eye sight of fighter pilots for night flying. If I remember correct, it states that any white light glimpsed once the eyes have become totally dark adapted, which in reality can take anything up to as long as an hour to become complete, will immediately destroy the dark vision for anything up to twenty to thirty minutes or more :)

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