The Camera Essay Research Paper The most — страница 3

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angle of an angled plane onto another angled plane where it too reflects the light. Then it travels through another perpendicular plane. It then travels through the eye piece or viewfinder. The shutter is controlled by a microprocessor in most SLRs, but can also be manual in many older ones. The mirror will flip up and an instant later the shutter will expose the film for the allotted amount of time. The way the focal plane shutter works is it uses a slit to uniformly expose each piece of film for the given time, or for long exposures just opens up fully. The leaf shutter serves the same purpose as the focal plane, but it has a system of over lapping leaves that open and expose the film all at once every time, slow of fast shutter speeds. The next and most important things are

the lenses. The lens is the eye of the camera just as the film is the retina. It brings light from the subject to the film. The lens can be a single lens of a series of lenses all to serve one purpose. The camera obscura was the first camera to be fitted with a lens. Its purpose was to sharpen the image on the paper inside the camera. It used a convex or converging lens. In the 19th century, the growing photography industry had a growing demand for specialized lenses specifically for the camera. The development came in two fronts. The first was an invention of new types of glass and the second was a development to combine several pieces of glass to create better lenses. Today s modern lenses are actually made up of several lens elements and assembled in a lens barrel with an

aperture ring and focusing ring. The focusing ring sharpens or blurs the image by changing the distance between some of the lens elements. The aperture ring controls the amount of light entering the camera. Different lenses have different focal lengths to perform different photographic tasks. The focal length is the distance from the central point in the lens to the plane of focus on the film. Lenses are categorized by their focal lengths and maximum aperture. Larger focal lengths produce larger images and greater aperture means more light can enter the lens. Lengths are determined by measuring the distance from the central point to the plane of focus, when the lens is focused at a distant point on the horizon called infinity. Short length lenses are called wide-angle lenses,

because they produce wider angles of view. While shorter lengths are called telephoto and produce a smaller angle of view. Also wide angle lenses produce distant objects while telephoto lenses produce closer objects. Another of the lenses, and one of the most popular, is the zoom lens. These lenses offer a wide variety of focal lengths. A user can change the length just by pushing a button on more automated models or turning a ring on older models. True-zooms stay in focus at any focal length, or need minimal adjustment. Varifocal zooms on the other hand must be adjusted every time a new length is selected. This is very annoying unless your camera has an auto focus feature. There are many special tasks that must be performed in photography. There are a variety of lenses to

satisfy each one of these tasks. On of the most common specialized tasks is close range photography. A lens called a macro lens will extend the range of focus to a mere few inches in front of the lens. On there own, macros produce an image size of +. An extension ring can correct this and increased image size to 100%. Another task is photomicrography, an extension on the macro principal. It uses a special connecting lens to allow the camera to be attached to a microscope. There are so many types of lenses for so many tasks. It would be nearly impossible to name them all and their purpose. Aperture is one of the most essential parts of photography. It allows light in or restricts it. It helps with exposure and in conjunction with focal length, creates what is called depth of

field. The lens diaphragm controls the aperture with overlapping leaves. Each setting is given a numerical representation. These are called f-stops. The formula to get the f-stops is: Where Lf is the focal length and Da is the aperture diameter. The f-stops are inscribed on the aperture ring. Some typical f-stops are: f/2, f/2.8, f/4, f/5.6, f/8, f/11, f/16. F/2 represents a large aperture. F/16 represents a small aperture. All lenses come rated with a maximum aperture, that is the maximum allowed amount of light entering the lens. The larger the maximum aperture the larger the lens must be. As mentioned before, aperture is a major ingredient in depth of field. Depth of field is simply the depth at which objects focus. A large aperture produces a small depth of field. Long focal