City skyglow, contrast and darkness eye adaption.

Discuss the greatest threat to amateur astronomy today

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adrian lord
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Joined: Tue Apr 11, 2006 6:48 pm
Location: Norfolk
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City skyglow, contrast and darkness eye adaption.

Post by adrian lord »

I live and observe in London, started observing in March of this year. I have been pleasantly surprised by just how much I have been able to see depite the major disadvantages.

I have noticed that dark adapted eyes can be a distinct disadvantage in badly light polluted skies when there is a lot of atmospheric skyglow - you see the glow and this hammers contrast and apparent transparency. Go inside, put the light on, go back out and hey presto the skies have suddenly "improved" dramatically, only to gradually "deteriorate" again over several minutes.

Am I mad or have others noticed this ironic reversal of the norm?
TMB/APM 152 apochromatic Refractor is my weapon of choice!

Scrumpy
Posts: 408
Joined: Fri Nov 18, 2005 5:55 pm
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Re: City skyglow, contrast and darkness eye adaption.

Post by Scrumpy »

adrian lord wrote:Am I mad or have others noticed this ironic reversal of the norm?
No! You're not mad but please stay where you are and don't run away if you see men in white coats approaching :wink:

Even in badly light polluted skies, dark adapted eyes are still able to see more stars.

You might see a darker sky when you first move from a bright room to outdoors but you'll also not see many stars! Contrast between the initially dark sky and ground based objects can appear to worsen but contrast will improve in the sky itself.

Kieran

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