Focal Length
September 13, 2008
Focal length of a lens is calculated by the distance between the centre of the lens and film or sensor. Based on the focal length shutter speed and aperture setting is determined. Focal length is a basic factor that determines depth of the subject taken using different lens. Taking natural photography like mountains, valley, scenery needs wide angle photography to ensure the entire subject is been captured like wise taking wildlife or bird picture which is very small there rise need to focus on the subject to get the image bigger by telephoto methods. All this criteria is synthesized by the perfect combination of lens with the essential focal length.
There are different focal length lens are available such as 24mm, 35mm, 50mm, 10mm, 200m, 400mm, 800mm and to the maximum of 1200mm in which 24mm to 1200mm are the focal length of the lens which is written on the lens. We need to look in many approaches to the subject when we work on different photographic assignments. This approach invokes us to work on many depth and dimension of the photography like long shot or close up shot. For all this assignments, we need to select lens with suitable focal length. Lens is categorized based on focal length like wide angle, normal and telephoto.
Lens having focal length less than 50 mm is suitable for taking wide-angle photography. Lens having focal length more then 50 mm is suitable for close up shots and are considered telephoto lens. Lens with focal length of 50mm is considered as normal lens and correspond to our normal vision. Popular zoom lens is also available to provide both combination of wide angle and enough telephoto for good close up shots. 35mm film camera zoom lens from Nikon is one among them that provides focal length of 28mm-105mm for good wide-angle photography as well as telephoto reach for good portrait lens. In digital camera image sensor comes in different size and focal length is expressed in different values. Larger image sensor uses larger lenses and small image sensor uses smaller lenses to ensure all the area of the image sensor is covered.
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