Author Topic: Future of Light Pollution Reduction Filter  (Read 441 times)

Akira

  • Homo jezoensis
  • NG Supporter
  • **
  • Posts: 11649
  • Tokyo, Japan
Re: Future of Light Pollution Reduction Filter
« Reply #15 on: September 23, 2022, 08:07:42 »
The level of air pollution and cloud must also be factors - if the air were clear then there would be nothing for the light to illuminate and it would just pass out to space?

Good point.  Unfortunately, however, the air pollution over Tokyo (and I would bet this applies virtually all big cities) is bad enough for various particles in the air to reflect the light coming from the city to cause light pollution. :(


Ilkka, Hugh, and Colin, thank you for chiming in.

Not only the satellites but also the airplanes flying over big cities are not-so-minor annoyance that ruin the night photography.  I hope the directional control (downwards) of LED lights will be more sophisticated to reduce the meaningless radiation into the sky.

Colin, no worries about straying!
"The eye is blind if the mind is absent." - Confucius

"Limitation is inspiration." - Akira

Øivind Tøien

  • NG Supporter
  • **
  • Posts: 1535
  • Fairbanks, Alaska
Re: Future of Light Pollution Reduction Filter
« Reply #16 on: September 23, 2022, 09:41:06 »

Reflectivity of the ground also has strong influence on effective light pollution. I see an increase in background exposure at zenith of up to two EVs once there the snow comes on the ground and in the trees - only a smaller part of that is the haze/ice fog (vs. that clear air in the fall). So there is a rather narrow window of really good conditions - snow typically stays on the trees until it melts in early spring time, which improves things a little.  On top of this we have the "light pollution" from the aurora, that tend to be more frequent around equinoxes in fall and spring...

I thought I was going to have a good imaging session on the Veil nebula the other night, but it took longer than expected to get it going, and once I got outside again for my first check, I found that clouds suddenly had drawn over after only 19 minutes. Planets are getting better these days, so that is an alternative when light pollution get too troublesome, although seeing is another matter then.
Øivind Tøien

Akira

  • Homo jezoensis
  • NG Supporter
  • **
  • Posts: 11649
  • Tokyo, Japan
Re: Future of Light Pollution Reduction Filter
« Reply #17 on: September 24, 2022, 12:13:49 »
Reflectivity of the ground also has strong influence on effective light pollution. I see an increase in background exposure at zenith of up to two EVs once there the snow comes on the ground and in the trees - only a smaller part of that is the haze/ice fog (vs. that clear air in the fall). So there is a rather narrow window of really good conditions - snow typically stays on the trees until it melts in early spring time, which improves things a little.  On top of this we have the "light pollution" from the aurora, that tend to be more frequent around equinoxes in fall and spring...

I thought I was going to have a good imaging session on the Veil nebula the other night, but it took longer than expected to get it going, and once I got outside again for my first check, I found that clouds suddenly had drawn over after only 19 minutes. Planets are getting better these days, so that is an alternative when light pollution get too troublesome, although seeing is another matter then.

Hmm...I forgot about the reflection of the snow.  Simply because I've never seen the aurora, I would rather welcome it, but it surely will a major hindrance for the astrophotography.
"The eye is blind if the mind is absent." - Confucius

"Limitation is inspiration." - Akira