WEBVTT - How do instant cameras work?

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<v Speaker 1>Slash brain Stuff. Him Marshall Brain with today's question, do

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<v Speaker 1>you remember the Polaroid camera with the instant film? How

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<v Speaker 1>did that film? Wark? How could you take a picture

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<v Speaker 1>and have the picture developed right in your hand in

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<v Speaker 1>just a minute or two instant camera film is remarkable

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<v Speaker 1>because it has its own built in developing studio. To

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<v Speaker 1>understand how this works, you need to understand the basics

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<v Speaker 1>of traditional photographic film. This has mostly been replaced by

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<v Speaker 1>digital cameras today, but it's still interesting and it's a

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<v Speaker 1>great chemistry experiment. Film is a plastic base coated with

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<v Speaker 1>particles of silver compound that are sensitive to light. Black

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<v Speaker 1>and white film has one layer of silver compound, while

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<v Speaker 1>color film has three layers. The top layer is sensitive

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<v Speaker 1>to blue light, the next layer is sensitive to green,

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<v Speaker 1>and the bottom layer is sensitive to red. When you

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<v Speaker 1>expose the film, the sensitive grains of each layer react

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<v Speaker 1>to light of that color, forming metallic silver at that layer.

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<v Speaker 1>This gives you a chemical record of the light and

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<v Speaker 1>color pattern. To turn this into a picture, you have

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<v Speaker 1>to develop the film. One developer chemical turns the exposed

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<v Speaker 1>particles into metallic silver. The film is then treated with

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<v Speaker 1>three different die developers containing die couplers. The three die

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<v Speaker 1>colors are cyan, a combination of green and blue light,

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<v Speaker 1>Magenta a combination of red and blue light, and yellow,

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<v Speaker 1>a combination of green and red light. Each of these

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<v Speaker 1>die coupler types react with one of the color layers

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<v Speaker 1>in the film. In ordinary print film, the die couplers

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<v Speaker 1>attached to particles that have been exposed. In color slide film,

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<v Speaker 1>the die couplers attached to non exposed areas. Developed color

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<v Speaker 1>film has a negative image, the colors appear opposite of

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<v Speaker 1>the colors in the original scene. In slide film, the

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<v Speaker 1>two dyes that attached to the unexposed area combined to

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<v Speaker 1>form the color captured at the exposed area. For example,

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<v Speaker 1>if the green layer is exposed, yellow and cyande will

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<v Speaker 1>attach to either side of the green layer, but the

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<v Speaker 1>magenta dye will not attach At the green layer, the

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<v Speaker 1>yellow and cyan combined to form green. The instant camera

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<v Speaker 1>developing process combines colors the same basic way that slide

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<v Speaker 1>film does. It has the same layers of light sensitive

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<v Speaker 1>grains as traditional film, all arranged on a plastic sheet.

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<v Speaker 1>The film also contains several additional layers. However, these layers

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<v Speaker 1>contain all the necessary chemicals for the development process. Underneath

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<v Speaker 1>each color layer, there's a developer layer containing die couplers.

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<v Speaker 1>All these layers sit on top of a black base layer,

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<v Speaker 1>and they sit underneath the image layer, timing layer, and

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<v Speaker 1>acid layer. This arrangement is essentially a chemical chain reaction

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<v Speaker 1>waiting to be set into motion. The component that gets

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<v Speaker 1>the developing process going is the reagent, as in reagent,

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<v Speaker 1>a mix of a pacifier's alkali white pigment and other elements.

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<v Speaker 1>The reagent sits in a layer just above the light

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<v Speaker 1>sensitive layers and just below the image layer. Before you

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<v Speaker 1>take the picture, the reagent material is all collected in

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<v Speaker 1>a blob at the border of the plastic sheet, away

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<v Speaker 1>from the light sensitive material. This keeps the film from

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<v Speaker 1>developing before it's been exposed. After you snap the picture,

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<v Speaker 1>the film sheet passes out of the camera through a

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<v Speaker 1>pair of tight rollers. The rollers spread the reagent material

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<v Speaker 1>out into the middle of the film sheet, just like

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<v Speaker 1>a rolling pin spreading out dough. When the reagent is

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<v Speaker 1>spread in between the image layer and the light sensitive layers,

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<v Speaker 1>it reacts with the other chemical layers in the film.

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<v Speaker 1>The obasifier material stops light from filtering into the layers below,

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<v Speaker 1>so the film isn't fully exposed before it's developed. The

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<v Speaker 1>re agent chemicals moved downward through the layers, changing the

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<v Speaker 1>exposed particles in each layer into metallic silver. The chemicals

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<v Speaker 1>then dissolved the developer die, so it begins to diffuse

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<v Speaker 1>up toward the image layer. The metallic silver areas at

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<v Speaker 1>each layer. The grains that were exposed to light grab

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<v Speaker 1>the dies, so they stopped moving up. Only the dyes

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<v Speaker 1>from the unexposed layers will move up to the image layer.

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<v Speaker 1>For example, if the green layer was exposed, no being

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<v Speaker 1>jet to die will make it to the image layer,

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<v Speaker 1>but cyane and yellow will. These colors combined to create

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<v Speaker 1>a translucent green film on the image surface. Light reflecting

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<v Speaker 1>off the white pigment and the reagent shines through these

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<v Speaker 1>color layers the same way that light from a bulb

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<v Speaker 1>shines through a slide. There is one problem left to solve.

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<v Speaker 1>Recall that there was this opacifier that made it so

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<v Speaker 1>that light couldn't get in to expose the film. While

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<v Speaker 1>all this developing is taking place, how do you make

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<v Speaker 1>the image clear? It turns out that at the same

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<v Speaker 1>time these re agent chemicals are working down through the

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<v Speaker 1>light sensitive layers, other re agent chemicals are working up

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<v Speaker 1>through the upper film layers. The acid layer in the

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<v Speaker 1>film reacts with the alkali and opacifiers in the reagent,

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<v Speaker 1>making the opacifiers become clear. This lets you see the

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<v Speaker 1>image below. The timing layer slows the re agent down

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<v Speaker 1>on its path to the acid layer to give the

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<v Speaker 1>film time to develop before it's exposed the light, and

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<v Speaker 1>you can see it. When you watch the image in

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<v Speaker 1>a photo film come into view, you're actually seeing this

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<v Speaker 1>final chemical reaction. The image is already developed underneath. You're

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<v Speaker 1>just watching the acid layer clear up the opacifiers in

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<v Speaker 1>the reagent so the image becomes visible to you. This

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