Name: LENSES
Uploaded: 2020-03-30T04:34:44.000Z
Duration: 8 min 52 s
Description: Thousands of YouTube videos with English-Chinese subtitles! Now you can learn to understand native speakers, expand your vocabulary, and improve your pronunciation...

Adverbs of manner

and, oh, you probably can't really see me right now let's throw a lens on that camera.

Now look deeply into my eyes, we're seeing each other through

Now, light is coming off of my eye and going through

my glasses and into the camera lens, and then

out of your screen into the lens in your eye.

In fact, let me grab one, most camera lenses have many pieces

of glass stacked inside of them, so while

we call this single piece of equipment a lens, there's actually many different “lenses”

And we're gonna take a look with our eyeball lenses, at some optical DONGs, things you

Ricktu's Ray Optics Simulator is a great way to visualize how light moves around when

You can make beams, rays and other light phenomena, interact with various reflective and translucent

You can change a whole bunch of factors, like the density of the beams and the shape of

We'll get to that in a second, but first let's talk about why light can go through

You can't see through me, or at least I hope you can't

When a photon hits something opaque, like you or me, it either scatters away in a random

direction or it's absorbed by the material.

Transparent materials on the other hand don't absorb light, but instead let it pass right

through, and that's what a simple sheet of glass does.

The science of why this happens is very cool and very complicated, 60 symbols has a wonderful

video on the topic, you can check it out right here

but basically when light hits an object, the

energy in the photon is absorbed by the electrons in the object's atoms.

With glass, however, the price of entry is a bit too high, and the atoms in the glass

want more energy than visible light can provide, so the light just keeps on truckin.

This applies to visible light, but not so much for UV light.

Check out my video from last year where we use predator vision.

The word lentil is where the word Lens comes from.

Lentils were never used to make lenses or anything, but they look the same a basic lens

Anyway, lenses, or really any curved glass, bends the light that passes through it.

it takes advantage of two fundamental properties of light.

The first is that light slows down in certain types of materials, like air, water, and glass.

Now you might be saying “ i thought the speed of light was constant” well that's

Again, there's a lot of weird quantum stuff going on, but the important thing is that

once light enters other mediums, it's forced to interact with the other atoms hanging around,

and those interactions slow everything down.

The second property of light is that it is not just a particle, but also a wave, which

means it fluctuates in three-dimensional space.

Imagine a group of runners all running next to each other, tied together with ropes.

If the group starts running through mud at an angle, one of them will be slowed down

faster, and the others will have to change angles to stay parallel.

That's essentially what's happening when light curves through a cup of water or a camera

This allows us to do all sorts of crazy things to incoming light.

You probably have zoomed in to something with a camera before.

If you have, you may have also seen these levels of magnification measured in millimeters,

for example, this video is being shot on a 50mm lens.

That number measures the distance between the front lens and the back lens.

On this site you can get an idea of what focal lengths look like in real life.

You can mess with the actual zoom of the camera as well as the camera body that captures the

Well it's actually a very complex process to make sure that the image stays sharp and

consistent while changing magnification, and it involves many layers of glass of different

when you twist a zoom lens like this you're actually physically moving the piece of glass

Some lenses actually stick out when you do this.

What this does is move what's known as an “afocal zoom system,” which involves a

few concave lenses (lenses that bend light inward) with a convex lens between them (which

So as the light from the object you want to magnify comes in it gets focused and then

re-spread out to make the image appear bigger on the image sensor.

Keep in mind that there are some types of lenses that don't zoom, and they're called

prime lenses, oh and if you zoom in on your phone it's not the same process.

that's just the camera enlarging the digital image rather than actually bending the light

It's the same thing we do in our videos where we punch in to make it look like it's a closer

Ok, so you can zoom in all you want, but going back to the beginning of this video,

what about when everything is out of focus??

Michael just did a DONG episode on how to use a pinhole

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LENSES

process

determine

consistent

force