Can Anyone Explain Different Types Of Lenses And Also Explain How Camera Works?

A lens is made up of glass, plastic or some other transparent materials and is curved in shape. When light ray pass through a lens, the light ray change direction. A lens with a surface that curves is called concave lens. Cameras, projectors, telescopes, microscopes and spectacles all contain lenses, which bend the light that passes through them. We have two lenses in our bodies, one in each eye. The lens in a magnifying glass is a convex lens. A magnifying glass can be used to make small objects appear bigger.

Light rays which pass through a lens form as image. What you see, reflected by a mirror s also called image. A camera works a bit like eye. Light enters the camera through a hole called focus aperture. The lenses in front of the aperture focus the light onto the film. Film is sensitive to light and records the image. Camera lens cannot focus easily as eye lenses. Lenses have to move backwards any forwards. Some cameras can do this automatically. On other, photographer turns the focusing ring to make the image clear. At this point, the film would be spoiled if light reached it. So there is a shutter between film and the aperture.

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Millions of people wear spectacles to see clearly and to read without any difficulty. Cameras are used for photography. Magnifying glasses are used to study small objects. Projectors are used to show films on the screen, microscopes enable us to study very tiny organisms and with the help of telescopes we can clearly observe far distant objects, planets, stars and galaxies. All these optical instruments have one thing in common that is they all uses lenses utilizing the refraction of light.

A lens is a piece of transparent material such as glass or plastic that refracts light in a regular way. These are bounded by one or two spherical surfaces. Two main types of spherical lenses are generally used convex lenses and concave lenses.

Convex lens: convex lens is thick at the center and thin at the edges. It converges parallel beam of light at a point and hence is called a converging lens. It has three types:
double convex lens
plano- convex lens
concavo-convex lens.

Concave lens: a concave lens is thinner at the center and thicker at the edges. It diverges a parallel beam of light. The rays after refraction through a concave lens appear to diverge from a point. It is called diverging lens it has three types:
double concave lens
plano-concave lens
convex-concave lens.

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