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Scotopic Vision and the Filterless Moon

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#1 Refractor Paul

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Posted 24 January 2023 - 02:11 PM

I was searching for some paperwork and found an article I had saved from Astronomy magazine. In the October 2009 issue, in the article Explore 12 Great Lunar Targets, Michael Bakich said, "My late observing friend, Jeff Medkeff, introduced me to a better way..." [than using filters when observing the Moon] 

 

He suggested turning on a white light, so your eyes are using normal scotopic vision - the best for detail and color - rather than having partially dark-adapted vision. 

 

Has anyone tried this? How did it go?


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#2 SoCalPaul

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Posted 24 January 2023 - 02:14 PM

Wow, how interesting. Have to give this a try. Did the article suggest where to place the light with respect to your position at the scope?

 

Clear skies,

Paul



#3 Refractor Paul

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Posted 24 January 2023 - 02:18 PM

No, it was just the one sentence. Let us know how your experiment goes. 



#4 Astrojensen

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Posted 24 January 2023 - 02:42 PM

I've always done this, when observing the Moon. It's so much more comfortable and convenient. Makes it much easier to read the maps. Having even partially dark-adapted eyes can sometimes hurt, when you're observing the Moon, especially with a medium to large scope, at medium magnification or lower. And you sometimes need lower magnifications and a bright image, to enhance the contrast enough, for example to see colors in the Mare or subtle nuances in the crater rays.  

 

Some observing sites provide the light for free...

 

med_gallery_55742_4772_1986565.jpg

 

 

Clear skies!

Thomas, Denmark


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#5 frank5817

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Posted 24 January 2023 - 03:51 PM

Whenever I sketch the Moon I have always use plenty of artificial white light, no need to dark adapt at all.

Same with bright planet targets.



#6 maroubra_boy

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Posted 25 January 2023 - 12:59 AM

What, "dark adapted" with the Moon? Ha, ha, ha!! lol.gif

I have also heard of folks sketching the Moon using fibble red light. How does this compute??? This is a recipe for eyestrain and a half.

You NEED a well lit environment around you when dealing with the Moon. Your vision will be stunned in much the same way as going from bright sunshine into a room - the effect is the same as are the trip & safety hazards, just in the backyard.

I work exactly the same way as Frank with the Moon. Well lit all around me. Doesn't need to be lighting for a tennis match, just leaving the porch light on to help you see hazards. What hazards? An observing chair, a stray skateboard, steps, tripod leg, accessories table, family pets, even handling accessories.

Going all dark adapted as per DSO's is only for eyestrain & a safety risk whether you sketch or not. There is no dark adaptation with the Moon. Keeping lights on ends up making things easier for your vision & ultimately your experience at the eyepiece.

 

The pic below shows me at my scope about to do a sketch of the Moon.  The lighting that you see is what I have in the yard, just the porch light and my white-light headlamp.

 

Alex.

Attached Thumbnails

  • Alex sketching Moon - Copy.JPG

Edited by maroubra_boy, 25 January 2023 - 01:02 AM.

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#7 Refractor Paul

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Posted 25 January 2023 - 01:38 AM

I found a more detailed recommendation from Astronomy magazine...

 

"Some years ago, an observer found a better way of observing the Moon: Turn on a white light behind you when you observe between Quarter and Full phases. The light should be moderately bright (in the 60-watt range), but neither your eyes nor the eyepiece should be in direct view of the fixture. The addition of white light suppresses the eyes’ tendency to dark adapt at night. Not dark adapting causes the eye to use normal daytime vision, which is of higher quality than dark-adapted night vision. So, you’ll see more detail because you’re viewing with a better part of your eye."

 

https://astronomy.co...erving-the-moon

 

I'm socked in with clouds for a while, so I won't be able to try it yet, but this definitely was a jolt to help me look at our old familiar hobby in a new light and peer through decades worth of assumptions and habits and wonder what other hidden gems are out there. 


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#8 mikerepp

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Posted 25 January 2023 - 01:10 PM

Yes I do this not only with the moon but Jupiter too.  Get those color receptors going.


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#9 maroubra_boy

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Posted 25 January 2023 - 08:52 PM

This is why with sidewalk astronomy the Moon & planets are the best targets - no need for dark adaptation.

#10 SoCalPaul

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Posted 26 January 2023 - 09:54 AM

I found a more detailed recommendation from Astronomy magazine...

 

"Some years ago, an observer found a better way of observing the Moon: Turn on a white light behind you when you observe between Quarter and Full phases. The light should be moderately bright (in the 60-watt range), but neither your eyes nor the eyepiece should be in direct view of the fixture. The addition of white light suppresses the eyes’ tendency to dark adapt at night. Not dark adapting causes the eye to use normal daytime vision, which is of higher quality than dark-adapted night vision. So, you’ll see more detail because you’re viewing with a better part of your eye."

 

https://astronomy.co...erving-the-moon

 

I'm socked in with clouds for a while, so I won't be able to try it yet, but this definitely was a jolt to help me look at our old familiar hobby in a new light and peer through decades worth of assumptions and habits and wonder what other hidden gems are out there. 

Excellent, thank you. Will give this a try as the moon waxes over the next week or so.

 

Clear skies,

Paul




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