There are many different types of camera including1. Film2. Digital3. Compact4. Single-lens reflex5. Disposable6. Instant-picture7. Large format
A digital camera captures images electronically rather than on standard film stores them on removable memory cards. Images can then be transferred to a computer and printed out or sent over internet.
Some digital cameras can be connected directly to printers in order to print out photos, and many printers have slots for memory cards to be inserted. This makes transferring images to a computer unnecessary.
The Polaroid “instant-picture” camera uses slim envelopes of plastic instead of a roll of film. Inside is a sheet of film and a pod of chemicals that bursts to process the picture in just 90 seconds.
The single-lens reflex (SLR) camera may use either film or a digital sensor. It is popular with photographers for its versatility, and because the viewfinder shows exactly the same view that the camera will record. The lens can be interchanged with others to give a wide view or to magnify the subject.
In early cameras, the lens was focused by moving a bellows-a concertina-like cloth tunnel-in and out. Many photographers still use large-format bellows cameras for high quality studio work.
The first photograph was taken only about 180 yrs ago. Hundreds of yrs ago, the Chinese found that light entering a dark room through a pinhole would project a fuzzy image of the world outside onto the opposite wall. Many yrs later, in 1500 in Europe, a room like this was called a camera obscure, which is Latin for “darkened room”. In the 17th century some artists drew sketches with the aid of a camera obscure which had a lens instead of a pinhole to make the image sharper and brighter. The discovery of chemicals that darkened when exposed to light finally made it possible to fix the image permanently- on paper, on glass plates, or on film.
Today, digital cameras use light-sensitive electronic sensors instead of film. Sophisticated electronic technology in most cameras ensures that each picture gets the right amount of light and imperfectly sharp.