To make a photograph with a camera the "shutter release" button is pressed. Pressing the button opens the "shutter". The shutter is like a door. It covers the hole in the camera box. The shutter is behind the lens. When the shutter is closed no light can enter the camera box. When the shutter is open light can enter the camera. When the button is pressed the shutter opens and then closes. This happens very fast. The amount of time the shutter stays open for is called the "shutter speed". The shutter speed can change between 1/1000th of a second (0.001 s) to a few seconds. Normally the time taken for the shutter to open and close is far less than 1 second.
Some cameras have an "aperture ring". It controls how much light enters the camera box.
The photograph in a camera may be made on film or, if it is a digital camera, using an electronic sensor.
The picture the lens makes is recorded on photographic film. Film is placed inside the camera box. Light coming through the lens, aperture and open shutter shines on the film. Photographic film is coated with chemicals that react when light shines on it. Letting light shine on the film is called "exposing" the film.
There are many different types of photographic film. There are films for taking colour photographs and films for taking black and white photographs. There are different sizes of film. The most common size is "35 mm". It is called 35 mm because the width of the film is 35 millimetres.
Another difference between films is how sensitive they are to light. Films have a code number, called an "ISO number". The number tells how fast a film reacts when light shines on it.
Once the film has been exposed it is "processed". Processing has to be done in total darkness or the film will be exposed too much and the picture will be lost. The picture will become to transparent and the image will not appear as it was when the picture was taken. Processing stops the film reacting to light any more. After the film has been processed the picture can be seen on the film.
A photographic "print" is a photograph made on paper. A light sensitive paper is used. The picture on the film is placed in an "enlarger". An enlarger is a machine that shines light through the film and makes a bigger picture on the light sensitive paper. A chemical reaction happens in the paper, which turns the areas hit with light black when the paper is 'developed'. (The more light, the darker the area.) "Developing" makes the picture appear on the paper – now it is a photograph. Then the paper is put into other chemicals that make it not sensitive to light any more. This is called "fixing". Last, the paper is washed so that there are no more chemicals on it and then dried. Then it is finished.
Digital photography uses a digital camera. Sometimes it is called "digital imaging". Like other cameras a digital camera has a lens, aperture, and shutter. The picture the lens makes is recorded by a light-sensitive electronic sensor. A digital camera does not use photographic film to record a picture. Digital photographs are stored in storage devices such as SD cards. They can later be transferred to a computer. Paper prints can also be made from digital pictures. Digital cameras are also not expensive to use, as there is no film to buy.
One of the most important things when taking a photograph is focusing the lens. If the lens is not focused well, the photograph will be blurry. Autofocus cameras focus automatically when the shutter release is pressed. There are also "manual" focus cameras (usually older ones).
Three other things are important when taking a photograph. These control how bright or dark the photograph will be. The brighter you have it the more transparent the picture comes out, if you have it to bright the whole screen can turn out to be all white, if the camera settings are set to be to dark, well, then the picture will come out to dark. So it really depends on how you want the picture, some cameras automatically come in with the setting at 50%, this is most recommended if you want to take a normal picture, but if you want to adjust the settings, it is recommended to keep it between 45% and 75%.
A slower shutter speed, a bigger aperture, and faster film/higher ISO sensor all make a brighter picture. A faster shutter speed, a smaller aperture, and a slower film/lower ISO sensor all make a darker picture. A good picture is not too bright and not too dark. When it is too bright it would be called "overexposed". An automatic camera changes these things by itself when the shutter release is pressed.
Camera typesThough there are many types of cameras, all include five indispensable components: (1) the camera box, which holds and protects the sensitive film from all light except that entering through the lens; (2) film, on which the image is recorded, a light-sensitive strip usually wound on a spool, either manually or automatically, as successive pictures are taken; (3) the light control, consisting of an aperture or diaphragm and a shutter, both often adjustable; (4) the lens, which focuses the light rays from the subject onto the film, creating the image, and which is usually adjustable by moving forward or back, changing the focus; and (5) the viewing system, which may be separate from the lens system (usually above it) or may operate through it by means of a mirror.
Acronym
An acronym is a word whose letters are the first letters of other words. People often create a short acronym that means the same thing as a much longer phrase (set of words). This is faster and shorter to say then the long phrase.
Examples of acronyms are:
An acronym usually must be able to be spoken as word. Other abbreviations such as ASAP (as soon as possible), USA (the United States of America), ECU (European Currency Unit), FBI (Federal Bureau of Investigation), NBA (National Basketball Association) have combinations of letters that are not pronounced as a single word. People just say the letters, one after another.
These three-letter acronyms, and some more obscure four-letter ones such as ISDN are more often called initialisms.
The word "acronym" comes from the Greek acro ‘extreme’ and onymus ‘name’.
The world's longest acronym, according to the "Guinness Book of World Records" is NIIOMTPLABOPARMBETZHELBETRABSBOMONIMONKONOTDTEKHSTROMONT (). It is 56 letters long (54 in Cyrillic). It is from the "Concise Dictionary of Soviet Terminology" and means "the Laboratory for Shuttering, Reinforcement, Concrete and Ferroconcrete Operations for Composite-monolithic and Monolithic Constructions of the Department of Technology of Building Assembly Operations of the Scientific Research Institute of the Organization for Building Mechanization and Technical Aid of the Academy of Building and Architecture of the USSR."
Radio wave
Radio waves make up part of the electromagnetic spectrum. These waves are packets of energy with differing wavelengths, similar to visible light waves, X-rays or gamma rays, except longer.
A radio wave, like other electromagnetic waves, is similar to an ocean surface wave or any other type of wave. Both types of wave have a hill and valley shape, repeating over and over. A wavelength is measured as the distance from the top of one crest to the top of its neighboring crest. While the wavelength of visible light is very very small, less than one micrometer and much less than the thickness of a human hair, radio waves can have a wavelength from a couple centimeters to several meters. They also have a radio frequency.
The smallest radio waves are called microwaves. Shortwaves are not quite so small. There are also medium and long waves. Antennas designed to send and receive radio waves are usually similar in size to the wavelength they are to use. Many radio antennas (like those on cars) are made long because they receive signals of FM radio (a few meters, several feet) or AM radio (hundreds of meters, about a thousand feet).