Could you replace your eye with a camera?


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. Many of you know
that Physics Girl is part of PBS Digital Studios. And exciting news–
PBS Digital Studios has been nominated
for a Webby Award. So if you want to support
this amazing network of educational
channels on YouTube, check out the link in
the description and vote for PBS Digital Studios.

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