Your eyes are pretty amazing.
In a fraction of a second, they can
focus from infinity to, well, grab a ruler to see how close.
I've got five inches before it becomes blurry.
But there are some schmancy cameras out there.
How do they compare to your eyesight?
And would you ever want to replace your eyeball
with a camera?
It's eyeball versus camera smackdown.
[BELL DINGING]
Round 1-- Which one focuses better?
And what does it mean to be in focus?
Yeah, it means that your image is sharper and clearer,
but how do you make it sharp?
Imagine this enormous chocolate bunny
as a bunch of small, brown dots in the shape of the bunny.
Light rays hit each dot and bounce
off in diverging directions.
To form an image, you have to use a lens
to bend the rays back into a dot,
and then they diverge again.
If your camera sensor or your eyeball's retina
is right where that dot forms on that sweet spot,
the image will be in focus.
If their position is off, the dot is going to blur
and then all those dots will blur together
and you'll be out of focus.
So a camera focuses light with a glass lens, which
doesn't change shape, but it can move backwards and forwards
as you adjust the focus, and that
will put light from objects different distances away
and focus on the camera sensor, on that sweet spot.
Your eyeball, on the other hand, doesn't
have a lens that can move backwards and forwards,
but instead uses the ciliary muscles around the lens
to bend the shape of the lens so it focuses on objects
different distances away.
So thanks to those super fast muscles around your eye,
a healthy human eye can focus from infinity to about 10
inches in front of your face in a third of a second, which
is partially why, when you look around a room
and you're focusing on objects different distances away,
it kind of seems like everything's in focus,
because your eye is changing focus so fast,
your brain doesn't have time to notice
that things are out of focus.
Now, the best cameras claim that they focus about five times
faster than the human eye.
But they don't always focus on what you want them to.
Auto focus can get a bit manic.
An affordable auto focus is way less accurate
compared to your eye.
So for versatility, round one goes to the eyeball.
[BELL DINGING]
Which contender is better at capturing moving targets?
So a camera captures things that are
moving by using a really fast shutter speed.
That is, it opens and closes the shutter of the camera really,
really quickly.
In essence, you're freezing a moment in time.
Before cameras, humans didn't even know how horses galloped.
It wasn't until the 1870s when Eadweard Muybridge
took some of the first high-speed photographs
to figure out how horses move their feet when they run.
So we can't resolve a horse's gallop,
but we still have a lot of really cool tricks
to make sure that when you move around, you get a clear image.
If you move your head around, your eyes
will move the opposite direction of your head
to make sure that the same spot is
staying in the center of your field of view.
Your eyes don't necessarily move when you move your head around.
This is called the vestibulo ocular reflex.
Or if you've ever watched someone's eyes
as they're riding in a moving car,
their eyes flick back and forth, because they'll
follow an object, like a tree, until moves
out of their field of view.
And then they'll focus on the next image.
This is called the optokinetic reflex.
Think about how cool these reflexes are.
You definitely can't swing your camera back and forth
and hope to get a nice photo.
I tried.
So I'm going to call this one a tie.
Knowing how horses gallop is pretty cool.
But reading road signs, kind of important.
[BELL DINGING]
Final round-- which one is smarter?
OK.
So your eyeball has the processing power
of your brain behind it.
Those stabilizing reflexes, refocusing
in a fraction of a second, that's all your brain.
Plus, it's got some other really cool tricks,
like piecing together two different images
from either eye into one single 3D image or automatic color
correction in different lighting.
But this automatic color correction
is also why we can be fooled into thinking
square A is different from square B when they're the same
and why people argued over the color of this dress.
And camera technology is just getting
better and more intelligent.
Engineers have been able to replicate
some of the capabilities of our eyesight in cameras.
Cameras can automatically color correct in different lighting.
And some cameras can recognize faces.
But again, lots of these advances in camera technology
have been to mimic the human eye, which
has been the model for cameras, not the other way around.
So this round goes to the eyeball.
So the eyeball beat the camera in the smackdown.
[CHEERING]
But it was never a fair fight.
I mean, the eyeball has the processing power
of the brain behind it.
Now this all brings me to the question,
would you ever want to replace your eyeball with a camera?
Well, scientists are already experimenting
with this kind of cybernetics in devices
like the Argus II, which is a device where the wearer wears
a camera on some glasses that take a picture
and then send that to a converter box, which sends
an electrical signal back into electrodes implanted
on your retina that your brain then has to interpret
as something like sight.
One woman wearing the Argus II claimed
that she could see light and dark
and could distinguish some pixelated shapes.
So wearing this device, you don't automatically
see like a normal person.
Your brain has to take those electrical signals
on your retina and reinterpret those as something like sight.
But you might have a sense that's
different than any of the five senses that the rest of humans
have, which is a pretty cool notion.
For more information on how the eye sees,
check out this video I made on the perception of color.
Thank you so much for watching, and happy physics-ing.
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