Focal Length

Technology / Digital Cameras / Focal Length: Focal length is a measure of the distance (in millimeters) from the optical center of a camera's lens to its focal point, which is located on the image sensor. Because digital cameras' focal lengths are measured differently than traditional film cameras, manufacturers usually give a '35mm equivalent' focal length in their specs. This helps 35mm film photographers get a better idea of just how wide-angle or telephoto a digital camera will be in relation to their film cam. A typical digital camera's 35mm equivalent focal length might be 28-280mm, while its actual focal length measures 4.6-46mm. The reason that a range of numbers is given here (28mm to 280mm) is due to the fact that most digital cameras have a zoom lens, which can change focal lengths. A fixed lens has only one focal length. A camera lens's focal length can tell you a lot about what kinds of pictures it will be able to take well. With a long focal length, like 280mm, a camera is better able to capture far-off subjects (such a lens is also known as 'telephoto'). With a short focal length, like 28mm, a camera can capture the scene immediately before it more completely (this kind of lens is considered 'wide-angle').

Other Words for Focal

Focal Noun Synonyms: central, focused, concentrated, convergent, centred, centralized
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Other Words for Length

Length Verb Synonyms: extent, measure, span, reach, size, magnitude, dimension, measurement
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Equivalent Focal Length

Entertainment / Photography / Equivalent Focal Length: Distance in a lens between the front nodal point and the focal plane when the lens is set to focus a subject at infinity. In a telephoto lens the equivalent focal length is shorter than the back focus MORE

Afocal Lens

Entertainment / Photography / Afocal Lens: Lens attachment that alters the focal length of the camera lens without disturbing the distance between the lens and the film plane. MORE

Fixed Focal Length

Entertainment / Photography / Fixed Focal Length: Camera system whose lens cannot be interchanged for a lens of different focal length. MORE

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