Lesson 9 How do cameras work? Part 1

Digital cameras give a whole new meaning to the idea of painting by numbers. Unlike old-style film cameras, they capture and record images of the world around us using digital technology. In other words, they store photographs not as patterns of darkness and light but as long strings of numbers. This has many advantages: it gives us instant photographs, allows us to edit our pictures, and makes it easier for us to share photographs using cell phones (mobile phones), e-mail, and web sites.

How ordinary film cameras work

If you have an old-style camera, you'll know that it's useless without one vital piece of equipment: a film. A film is a long spool of flexible plastic coated with special chemicals (based on compounds of silver) that are sensitive to light. To stop light spoiling the film, it is wrapped up inside a tough, light-proof plastic cylinder—the thing you put in your camera.

When you want to take a photograph with a film camera, you have to press a button. This operates a mechanism called the shutter, which makes a hole (the aperture) open briefly at the front of the camera, allowing light to enter through the lens (a thick piece of glass or plastic mounted on the front). The light causes reactions to take place in the chemicals on the film, thus storing the picture in front of you.

This isn't quite the end of the process, however. When the film is full, you have to take it to a drugstore (chemist's) to have it developed. Usually, this involves placing the film into a huge automated developing machine. The machine opens up the film container, pulls out the film, and dips it in various other chemicals to make your photos appear. This process turns the film into a series of "negative" pictures—ghostly reverse versions of what you actually saw. In a negative, the black areas look light and vice-versa and all the colors look weird too because the negative stores them as their opposites. Once the machine has made the negatives, it uses them to make prints (finished versions) of your photos.

If you want to take only one or two photographs, all of this can be a bit of a nuisance. Most people have found themselves wasting photographs simply to "finish off the film." Often, you have to wait several days for your film to be developed and your prints (the finished photographs) returned to you. It's no wonder that digital photography has become very popular—because it solves all these problems at a stroke.

Vocabulary

string - цепь, серия, ряд

spool – катушка, бобина

developing machine - проявочная машина

compound – сплав, соединение

aperture [‘æpətʃə]- глазок, отверстие объектива 

weird [wiəd]– странный, необычный, таинственный

nuisance [‘nju:s(ə)ns]- неудобство, досада

at a stroke - в два счета; махом

Exercise 1

Find Russian equivalents to the following words in the text. Learn them by heart.

Ряд/серия, ловить, преимущество, редактировать/исправлять, мгновенный, крайне необходимый, пленка, катушка, светонепроницаемый, портить, нажимать, затвор, входить/проникать, соединение/сплав, чувствительный (к свету), линза, сохранить, погружать, серия/ряд (чего-то), противоположны/обратный, наоборот

Exercise 2

Match the opposites. There can be more than two opposites of one word.

String, spoil, slow, analogous, rim, exit, drawback, resistant, single item, hole, unnecessary, delete, series, advantage, lift up, light-proof, disadvantage, needless, edit, alike, instant, vital, shutter transparent, enter, similar, sensitive, lens, dip, store, reverse

Exercise 3

Solve the crossword

1							3
									5
			1			2									7
												6
		3					4		4
											5
					2
				6

Across

1) a thing consisting of two or more separate things combined together; a substance formed by a chemical reaction of two or more elements in fixed amounts relative to each other

2) to change something good into something bad, unpleasant, useless, etc.

3) several events or things of a similar kind that happen one after the other

4) change (text) on a computer

5) necessary or essential in order for something to succeed or exist

6) operating, behaving, or ordered in a way opposite to that which is usual or expected

Down

1) exert (прилагать) continuous physical force on (something), typically in order to operate a device

2) a piece of glass or other transparent material with curved sides for concentrating or dispersing light rays, used singly (as in a magnifying glass (лупа)) or with other lenses (as in a telescope)

3)  to put something quickly into a liquid and take it out again

4) keep or accumulate (something) for future use

5) the other way round

6) a set or series of things that are joined together, for example on a string; a series of things or people that come closely one after another

7) a cylindrical device on which film, magnetic tape, thread, or other flexible materials can be wound

Exercise 4

Fill in the sentences with the words from the box

series, vital, spoil, lenses (2), dipped (2), pressed, storing, shutters, compound, spoilt/spoiled (2), strings, vice versa

1) Common salt is a _________of sodium and chlorine.

2) The molecules join together to form long__________.

3) It is __________that the system is regularly maintained.

4) Our camping trip was __________by bad weather.

5) I have two pairs of glasses with different coloured___________ for different light conditions.

6) The tall buildings have__________the view.

7) He __________the brush into the paint.

8) I wanted HIM to come running to ME, not__________.

9) I won’t tell you what happens in the last chapter—I don’t want to ___________it for you

10) His first telescope was made from available __________and gave a magnification of about four times.

11) The movie consisted of a __________of flashbacks.

12) He __________a button and the doors slid open.

13) The fruit had been ___________in chocolate.

14) A small room is used for __________furniture.

15) A pair of windows with wooden __________allows for a good deal of incoming light.

Exercise 5

Answer the questions

1) How do digital cameras store pictures?

2) What is a film?

3) Why is a film wrapped up inside a tough, light-proof plastic cylinder?

4) What is a lens?

5) What is the peculiarity of a negative?

5) What are disadvantages of ordinary film cameras?

Lesson 10

How do cameras work?

Part 2

How digital cameras work

Digital cameras look very much like ordinary film cameras but they work in a completely different way. When you press the button to take a photograph with a digital camera, an aperture opens at the front of the camera and light streams in through the lens. So far, it's just the same as a film camera. From this point on, however, everything is different. There is no film in a digital camera. Instead, there is a piece of electronic equipment that captures the incoming light rays and turns them into electrical signals. This light detector is called a charge-coupled device (CCD). A CCD is an array of capacitors that are sensitive to light — when you hear cameras advertised by their resolution, it's the number of these capacitors that is being referred to. As particles of light (photons) strike the capacitors, they generate electrons. This creates an overall charge that can then be read as an indication of light intensity.

If you've ever looked at a television screen close up, you will have noticed that the picture is made up of millions of tiny colored dots or squares called pixels. Laptop LCD computer screens also make up their images using pixels, although they are often much too small to see. In a television or computer screen, electronic equipment switches all these colored pixels on and off very quickly. Light from the screen travels out to your eyes and your brain is fooled into see a large, moving picture.

In a digital camera, exactly the opposite happens. Light from the thing you are photographing zooms into the camera lens. This incoming "picture" hits the CCD, which breaks it up into millions of pixels. The CCD measures the color and brightness of each pixel and stores it as a number. CCDs don't read the color of the light, just its intensity, so to produce color photographs there must be a way of discriminating the intensity of the various colors of incoming light. These colors are known as the additive primaries: green, blue, and red. All the colors you see in a digital photograph are built of these colors.

Your digital photograph is effectively an enormously long string of numbers describing the exact details of each pixel it contains.