WEBVTT - How did instant cameras work?

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<v Speaker 1>Welcome to Brainstoff front House, stuff Works dot Com, where

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<v Speaker 1>smart happens Him Marshall Brain with today's question, do you

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<v Speaker 1>remember the polaroid camera with the instant film? How did

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<v Speaker 1>that film work? How could you take a picture and

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

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<v Speaker 1>a minute or two. Instant camera film is remarkable because

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

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

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 This has mostly been replaced by digital

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

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

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

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

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

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

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

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

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<v Speaker 1>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, magenta,

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

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

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

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

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

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<v Speaker 1>the die cup is attached to non exposed areas. Developed

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

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

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

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<v Speaker 1>to 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 cyan dye

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

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

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

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

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

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<v Speaker 1>sensitive 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 dive aveloper 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 pacifiers, 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>reagent chemicals moved downward through the layers, changing the exposed

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

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

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

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<v Speaker 1>The grains that were exposed to light grab the dies,

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

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<v Speaker 1>unexposed layers will move up to the image layer. For example,

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<v Speaker 1>if the green layer was exposed, no bin jet to

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

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<v Speaker 1>and yellow will. These colors combined to create a translucent

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

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

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<v Speaker 1>the same way that light from a bulb shines through

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

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

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

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<v Speaker 1>this developing is taking place. How do you make the

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

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

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

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

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

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

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<v Speaker 1>The timing layer slows the re agent down on its

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<v Speaker 1>path to the acid layer to give the film time

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<v Speaker 1>to develop before it's exposed to light, and you can

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

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<v Speaker 1>film come into view, you're actually seeing this final chemical reaction.

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<v Speaker 1>The image is already developed underneath. You're just watching the

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<v Speaker 1>acid layer clear up the opacifiers in the reagent so

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<v Speaker 1>the image becomes visible to you. For more on this

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<v Speaker 1>and thousands of other topics, is that how stuff works

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<v Speaker 1>dot com and don't forget to check out the brain

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