My really dumb question of the day ...

I'm near sighted so when I don't have my contacts or glasses on and I focus on something a few inches away it looks like my eyes are on live view at F1.4 LoL

roakey wrote in post #13402876
It wasn't so much that you saw the bullet, it was more like you realized that you had seen (past tense) the bullet.

The crazy thing is that due to processing delay, you don't actually ever "see" in real time. Your brain takes all of it's sensory experience and pieces a scenario together of what just happened, discarding what it considers irrelevant, filling in some holes based on experience, and then you become conscious of it. We are living maybe 100-200ms in the past, and that past has been filtered for us.

jwccds

Yes, I made some presumptions about "the blind person" but you must get the general idea. In all those examples (except missing eyeballs), there is a factor preventing conversion.

Regarding your hearing versus listening example, same thing as I said earlier. Conversion. The physical world must be converted into an electrical transmission that the brain processes. You made my point: the processing is critical to seeing... Whether it be light waves trasmitted through the eyes into an electrical pulse that the brain processes into an image (the image can be conciously acknowledged or buried in the subconcious, again I'm not arguing against that notion) or whether it be sound waves echoing off phsycal objects, transmitted throught the ear drum and the brain amazingly processes sounds into images. It's my same premise. Processing is critical to seeing. Conciousness of processing is after the fact. By the way, echolocation is not the same as seeing. Different topic.

In the popcorn example, you said the mind digests it. Therefore, you imply processing. You just described the conversion process. If eye picks it up and mind doesn't digest it - that is, error in conversion or transmission - the person never saw it. The image never passes into either the conscious or subconciousness. Could be that he blinked at that very moment it was flashed on screen... or a sudden migraine blurs his vision. Whatever the case, passing through the physical lens is not seeing without converting the physical light spectrum into the mind.

DavidG. wrote in post #13403431
What is the ISO range of our eyes?

Dunno, but the mixture of rods vs cones in the retina does allow for a sensitivity adjustment that can be compared to ISO.

ETA: Just spent a few minutes googling and claims run anywhere from 800 to ~60k as an upper limit. Lower limit is probably something like ISO 1.

There is another consideration - our retina are very similar to a digital sensor, rods and cones that react to light hitting them. Something moving across might be moving faster then the rods/cones can react and register long before it's actually going particularly fast.

A large bright canon shell a distance away is going the same speed as one closer, but we might see the distant one and not the closer one simply because the closer one is moving across the retina faster in relation to the width of the retina itself - 100 metres far away is still in our field of view, close-up and it's 100mm or less, you'd never see it!

So, we have many variables:
Object speed and distance, relative brightness (the 'see-ability' of it).
Speed of reaction of an individuals retina (I believe they do vary).
Nerve transfer speed; probably very close in all people, and it has a maximum limit.
Brain processing speed (again, it may vary).

Oh, there's another, harder to quantify.. our brain tends to 'ignore' image data that does not fit certain criteria. We truly don't notice some things, yet others do.

I believe top echelon military people, and FBI, maybe good Police/detectives, etc, would see things, notice thing and respond long before an everyday 'Joe' would.
Even high 'rank' photographers would lose, and they themselves would see things others not in photography would miss (mainly photography related, litter, etc).

I don't believe people could see bullets though - 1000 M/s muzzle velocity is not 'extra' fast for a weapon, yet is 1000th second per metre, I don't even think our eye/brain combination can react that fast to see it. The information hitting the retina is gone before the cells have reacted to it.

Nathan wrote in post #13403130
Never said speed of light was the question. However, the question is also not the speed thought processing. If we're processing something, then we've already seen it. We're beyond the point of discussion already. I'm talking about that stage between light and thought.

The question is what is the speed of light-to-thought conversion. I'm saying that the conversion must take place for something to be seen. Think of a blind person. You can throw all the projectiles you want in front of the person and the transmission of that light may even enter through the person's eyes. However, there is an error in conversion and nothing is ever seen.



My argument is that if something flashes before your eyes at the speed of light and the conversion process occurs at a lower speed, then it is possible that the image was never seen. Think of it like frames per second of a shutter... something can occur during the actuation. In my analogy, it is the actual occurence of conversion.

I'm not differentiating between conscious and subconscious. Again, I think at that point we can agree that something's been seen, i.e. the mind is already processing information that was converted from light into thought.


Exactly. But I'm talking about the transition step from light entering the lens to the creation of what is seen.

Again... we're going off topic.

Fluffbutt wrote in post #13404138
I don't believe people could see bullets though - 1000 M/s muzzle velocity is not 'extra' fast for a weapon, yet is 1000th second per metre, I don't even think our eye/brain combination can react that fast to see it. The information hitting the retina is gone before the cells have reacted to it.

That is about average for a rifle bullet but pistol bullets are generally about 1/3 that speed which makes them much easier to see.

It should also be noted that direction of travel is a big part of the equation. A bullet passing across your line of sight could be easy to miss (impossible to see, rather) while a bullet travelling nearly parallel, such as a bullet you have fired, would be much easier to see. With a camera this would be the difference between a faint smudge across the frame in once case and an indistinct but much darker "blob" in one section of the image for the other.

When the lighting conditions are right for it, it is not uncommon to see the bullet when shooting at extended ranges and using a scope. At 1000m the bullet has often slowed down to around 300m/s and enough time has passed that you have recovered from the recoil and are looking through the scope at the target, which the bullet will hopefully be passing near.

The first time I ever saw a bullet in midair was using a .45 caliber carbine at 100meters. The bullet is sub-sonic when it leaves the barrel and loses velocity quickly so at 100m it is moving relatively slow. In the right light it was very easy to see the bullet as it "fell" into the targets.

krb wrote in post #13403663
Dunno, but the mixture of rods vs cones in the retina does allow for a sensitivity adjustment that can be compared to ISO.

ETA: Just spent a few minutes googling and claims run anywhere from 800 to ~60k as an upper limit. Lower limit is probably something like ISO 1.

And the sensitivity could be substantially greater - if the light-sensitive cells weren't underneath a whole load of other cells. Yup, all the nerve cells that carry information from the rods and cones to the brain all run on the top surface of the retina. It's a real shame our eyes weren't designed. Or, if they were, the designer was a total moron.

so does how "sensitive" a person is relate to his "sensor" I know that's big around here.
are you a 26 or 35?

hollis_f wrote in post #13406627
And the sensitivity could be substantially greater - if the light-sensitive cells weren't underneath a whole load of other cells. Yup, all the nerve cells that carry information from the rods and cones to the brain all run on the top surface of the retina. It's a real shame our eyes weren't designed. Or, if they were, the designer was a total moron.

LOL. Can I quote that?

Terms of evolutionary theory, though... aren't we all just prototypes? Ever new model is modified just enough to adjust to our surroundings? Enough to survive, that is. There may be some ingenius new design, but will be undiscovered until the circumstances around it reveal its strengths? Maybe we have some superseers in our population.

Fluffbutt wrote in post #13404138
A large bright canon shell a distance away is going the same speed as one closer, but we might see the distant one and not the closer one simply because the closer one is moving across the retina faster in relation to the width of the retina itself - 100 metres far away is still in our field of view, close-up and it's 100mm or less, you'd never see it!

So, we have many variables:
Object speed and distance, relative brightness (the 'see-ability' of it).
Speed of reaction of an individuals retina (I believe they do vary).
Nerve transfer speed; probably very close in all people, and it has a maximum limit.
Brain processing speed (again, it may vary).

Oh, there's another, harder to quantify.. our brain tends to 'ignore' image data that does not fit certain criteria. We truly don't notice some things, yet others do.

A much deeper analysis than I am able to offer myself. Thanks! If I understand you correctly, it helps my conversion argument along.

calvinjhfeng wrote in post #13401374
I wish we had a faster shutter speed with our eyes... then we can probably see the path of a high speed projectile.

Use a tracer round... you will see it well enough

It's routine for a sniper team to have a shooter and an observer. The observer watches the flight of a regular (high velocity round) and gives the shooter corrections so that the second shot is on target. Of course, this is only possible because the projectile's flight is almost parallel with the observer's line of sight.