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Comment by retrac | Hacker News Reader

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.

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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.

This is genius.

Wait no way? That’s where the pirate eye patch trope comes from? There was a practical reason?

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…

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.

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...

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.

People are bullshitting just the same about topics they know nothing about. They often also won't shut about when others tell them and even when they themselves know that they know nothing. To some extent this is necessary for humans to function at all, and the scientific process starts out from uneducated guesses and rigorously refines them and casts away what doesn't hold up to empiric data.

Optical illusions are evidence of the pile of hacks that our senses and our consciousness use to make sense of the world. I think it is really difficult to fully disengage from the biases this induces, and we are sadly best at perceiving such flaws in others. This might be one of the reasons why humans have to socialize with other humans to maintain mental health.

This would explain why only pirates wear them rather than also ordinary seamen.

There's no evidence that this use was real. Mythbusters tried it and said the trick itself does work (which any of has may already know), but who knows if it was even practical in a pirate boat, vs the loss of stereo vision etc.

The whole idea of pirates wearing eyepatches seems simply the replication of one particularly colorful pirate archetype over centuries of literature and tales.

I feel like the advantages of stereo vision may be oversold in this scenario. At the distances that sailing vessels would engage there's limited need for binocular depth cues - they really only start to come into play at the point where you would begin a boarding action

But the idea of the patches-for-night-vision is precisely to have one eye covered during the boarding, so when you enter the insides of the enemy boat that eye is ready for seeing in the dark.

Have you ever tried to climb a rope ladder on a moving ship?

Stereo vision is helpful on ships (and allmost everywhere else where you need eyes), even when not boarding.

I don't have binocular vision. I lived aboard a sailboat for a few years. I'm quite active with rock climbing etc and I honestly don't think I would be able to do anything better if I had binocular vision...

Just a thought

Good for you!

But I know I am worse doing climbing etc. with one eye.

It is probably something you can train and get used to, that it is not such a big deal, but I cannot imagine doing it on the same level one eyed.

But then again, you did not have enough motivation to spend time learning it. A pirate captain might have enough to actually train this way.

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.

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.

Last night in particular, hiking through the forest there was no need for a flashlight at all.

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.

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.

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

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.

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

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