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ritu.dhawan
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Electronics & Gadgets
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1:29 PM on April 29, 2008
Kannan's Answer
Due to the optical properties of photographic lenses, only objects within a certain range of distances from the camera will be reproduced clearly. The process of adjusting this range is known as changing the camera's focus. There are various ways of focusing a camera accurately. The simplest cameras have fixed focus and use a small aperture and wide-angle lens to ensure that everything within a certain range of distance from the lens, usually around 3 meters (10 ft) to infinity, is in reasonable focus.
Most consumer digital cameras often have more than one focusing mode. When using an automatic mode, focus is locked when the shutter-release button is pressed half-way down. Correct use of the two-step shutter button is key to obtaining proper focus.
The LCD or electronic viewfinder indicates when, and sometimes where, focus is locked. There is a visual indicator, such as a small lamp or change in color of the focus indicator, that confirms when focus is achieved.
Auto Focus
Single (or one) area focus - camera focuses on a subject in the central area of the screen. Focus adjusts according to the distance of the subject. This is the most common focus mode.
Continuous autofocus - focuses continually on a subject; useful when shooting slow moving subjects. However, if your photos are often poorly focused switch to single area focus. Continuous auto focus consumes more battery power.
Spot focus - camera focuses on a very precise center area of the screen.
3, 9-area focus - camera automatically focuses using one or more focus points. The focus positions change according to each subject, focusing on a number of objects within a scene.
Face-Priority AF - In 2005, Nikon introduced Face-Priority auto focus, which is activated when select CoolPix digital cameras are switched to Portrait mode. A special digital detection program scans for facial details and then controls auto focus operation based on the location of the detected face in the scene.
Even if the subject moves, or as the photographer recomposes the picture, Face-priority AF keeps focus on a subject's face.
Pre-focus
Prefocusing can be effectively used when there is a pre-determined, similar distance between the camera and subject. Focus is fixed until you press the focus button again or switch to a different focus mode. Digital cameras have different methods of prefocusing, so check the manual.
Manual Focus
Manual Focus Area- focus on a portion of a scene when not centered in the frame. Use one of several focus area indicators. Select the area by toggling a cursor button. This method is useful for close-up and macro shots.
Answered at
10:56 PM on May 01, 2008
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