4 ms·

If you want the best possible view with the naked eye, give them a chance to adapt to the dark properly. The human eye is about 100,000 more sensitive after an

by retrac 2y ago

If you want the best possible view with the naked eye, give them a chance to adapt to the dark properly. The human eye is about 100,000 more sensitive after an hour in total darkness. A smartphone screen or car headlight is enough to undo it.

kragen 2y ago
car headlights are brighter than the sun from a short enough distance; perhaps you think we can guess what distance you're talking about seeing the car headline from, but actually you have to be explicit about it
- throwaway_ab 2y ago
  In the dark notice how much light comes from a phone and how much that illuminates the person holding the phone. A car headlight shining your way from hundreds of meters even over 1km will often illuminate that person far more than their phone screen. So if the phone screen is enough to undo the hour long eyes adjusting to the dark duration, then the car headlights at almost any realistic distance causes an undo.
  - kragen 2y ago
    a headlight a kilometer away may be spread over 36000 square meters including your face. (more detailed info on headlight antenna gain would be appreciated.) a 1200-lumen high beam over that area is 0.03 lux a 500 nit phone screen emitting over about a steradian from an 80mm × 160mm area is 6.4 lumens, but at night you usually turn it down to minimum brightness, say 0.6 lumens. (i haven't measured.) at a distance of 300mm that steradian is 0.09m², so it's about 6 lux so the cellphone is about 200 times brighter than the headlight at that distance, and that's also observable from looking at people using cellphones walking on the highway but the person i was asking for more detail didn't specify that the headlight is pointed at your face; and in most situations where you can see headlights, they're not pointed at you. that's just a detail you filled in
lambdasquirrel 2y ago
Makes sense.. all the serious astronomy apps are in black and red, and back before we had phones, we used to use red flashlights if we needed to consult our charts.
- dylan604 2y ago
  just like all of the 80s military action films with red filtered flashlights or CNC rooms on ships. sometimes, meme like content isn't just made up. as an amateur (at best) astro type person, you learn very quickly how true how quickly a brief flash of white light can ruin your night vision. walking around during the day without sun glasses can also extend the amount of time it takes your eyes to acclimate to the dark. however, once you do allow your eyes to acclimate to the dark, it is amazing to me still how much we can actually see.
  - solarwindy 2y ago
    Last night in particular, hiking through the forest there was no need for a flashlight at all.
    - dylan604 2y ago
      On full moons, you can read a book and see the shadows cast by the moonlight. It's fun to take someone to see it for the first time who originally do not believe the shadows are possible.
      - solarwindy 2y ago
        Fun thing about Friday, there was no moon to see by. But absolutely, the full moon on a clear night can be a floodlight, especially with snow on a nighttime ski tour.
punnerud 2y ago
Use the old pirate trick and keep an eye patch over one of the eyes, and switch when going outside. They used it to be able to see inside the boat going from bright sunlight.
- noman-land 2y ago
  This is genius.
- olive247 2y ago
  Wait no way? That’s where the pirate eye patch trope comes from? There was a practical reason?
  - xanderlewis 2y ago
    I had assumed it was because, being a pirate, you were more likely to have had one of your eyes poked out during some sort of mêlée. But that’s much more interesting…
    - scientism 2y ago
      I've read another theory: It's because of the sun damage to their eye from using a sextant for navigation. Haven't been able to confirm it though.
      - samus 2y ago
        Such damage is creeping and the brain can just hallucinate the blank patches in the vision away, until only like 10% of the retina is left and it just doesn't work anymore. These days, dumbass laserheads are the most likely to suffer from that problem. It's amazing how much of our conscious experience is hallucination, and yet a lot of people are disparaging LLMs for doing just the same...
        crashmat 2y ago
        probably because when humans pay full attention and think clearly they can not hallucinate for 99% of things they can sense (disregarfing optical illusion), but there is no 'pay attention and dont hallucinate' switch for LLMs.
mypalmike 2y ago
Yup. Here in the city of Seattle, I went to a park where there were lots of people and unfortunately, lots of light. I could see some wispy light in the sky, and it was interesting to look at but not very dynamic. After I got home, I just laid down in the grass in the back yard where it's fairly dark. After about 15 minutes, I had a pretty good view of what looked a bit like streaky clouds throughout the sky. It was still somewhat faint but the movement was fantastic to watch.

by retrac 2y ago

kragen 2y ago

car headlights are brighter than the sun from a short enough distance; perhaps you think we can guess what distance you're talking about seeing the car headline from, but actually you have to be explicit about it

throwaway_ab 2y ago
In the dark notice how much light comes from a phone and how much that illuminates the person holding the phone. A car headlight shining your way from hundreds of meters even over 1km will often illuminate that person far more than their phone screen. So if the phone screen is enough to undo the hour long eyes adjusting to the dark duration, then the car headlights at almost any realistic distance causes an undo.
- kragen 2y ago
  a headlight a kilometer away may be spread over 36000 square meters including your face. (more detailed info on headlight antenna gain would be appreciated.) a 1200-lumen high beam over that area is 0.03 lux a 500 nit phone screen emitting over about a steradian from an 80mm × 160mm area is 6.4 lumens, but at night you usually turn it down to minimum brightness, say 0.6 lumens. (i haven't measured.) at a distance of 300mm that steradian is 0.09m², so it's about 6 lux so the cellphone is about 200 times brighter than the headlight at that distance, and that's also observable from looking at people using cellphones walking on the highway but the person i was asking for more detail didn't specify that the headlight is pointed at your face; and in most situations where you can see headlights, they're not pointed at you. that's just a detail you filled in

lambdasquirrel 2y ago

Makes sense.. all the serious astronomy apps are in black and red, and back before we had phones, we used to use red flashlights if we needed to consult our charts.

dylan604 2y ago
just like all of the 80s military action films with red filtered flashlights or CNC rooms on ships. sometimes, meme like content isn't just made up. as an amateur (at best) astro type person, you learn very quickly how true how quickly a brief flash of white light can ruin your night vision. walking around during the day without sun glasses can also extend the amount of time it takes your eyes to acclimate to the dark. however, once you do allow your eyes to acclimate to the dark, it is amazing to me still how much we can actually see.
- solarwindy 2y ago
  Last night in particular, hiking through the forest there was no need for a flashlight at all.
  - dylan604 2y ago
    On full moons, you can read a book and see the shadows cast by the moonlight. It's fun to take someone to see it for the first time who originally do not believe the shadows are possible.
    - solarwindy 2y ago
      Fun thing about Friday, there was no moon to see by. But absolutely, the full moon on a clear night can be a floodlight, especially with snow on a nighttime ski tour.

punnerud 2y ago

Use the old pirate trick and keep an eye patch over one of the eyes, and switch when going outside. They used it to be able to see inside the boat going from bright sunlight.

noman-land 2y ago
This is genius.
olive247 2y ago
Wait no way? That’s where the pirate eye patch trope comes from? There was a practical reason?
- xanderlewis 2y ago
  I had assumed it was because, being a pirate, you were more likely to have had one of your eyes poked out during some sort of mêlée. But that’s much more interesting…
  - scientism 2y ago
    I've read another theory: It's because of the sun damage to their eye from using a sextant for navigation. Haven't been able to confirm it though.
    - samus 2y ago
      Such damage is creeping and the brain can just hallucinate the blank patches in the vision away, until only like 10% of the retina is left and it just doesn't work anymore. These days, dumbass laserheads are the most likely to suffer from that problem. It's amazing how much of our conscious experience is hallucination, and yet a lot of people are disparaging LLMs for doing just the same...
      - crashmat 2y ago
        probably because when humans pay full attention and think clearly they can not hallucinate for 99% of things they can sense (disregarfing optical illusion), but there is no 'pay attention and dont hallucinate' switch for LLMs.

mypalmike 2y ago

Yup. Here in the city of Seattle, I went to a park where there were lots of people and unfortunately, lots of light. I could see some wispy light in the sky, and it was interesting to look at but not very dynamic. After I got home, I just laid down in the grass in the back yard where it's fairly dark. After about 15 minutes, I had a pretty good view of what looked a bit like streaky clouds throughout the sky. It was still somewhat faint but the movement was fantastic to watch.