Definitions
from The American Heritage® Dictionary of the English Language, 5th Edition.
- noun The ratio of the focal length of a lens or lens system to the effective diameter of its aperture.
from Wiktionary, Creative Commons Attribution/Share-Alike License.
- noun photography The
ratio of thefocal length of alens to itsdiameter ; ameasure of thelight -gathering ability of the lens.
Etymologies
from The American Heritage® Dictionary of the English Language, 4th Edition
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Examples
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Blaker explained this in another book, Field Photography (1976): ... at significant magnifications the choice of f-number is ... nearly always a matter for compromise between depth of field needs and the resolution of fine detail in the image.
Archive 2009-06-01 AYDIN 2009
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If your camera has manual controls, you can add more light to your shots by opening the aperture more widely (using a smaller f-number) and slowing the shutter speed (to, say, 1/125 or even 1/60 of a second).
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If your camera has manual controls, you can add more light to your shots by opening the aperture more widely (using a smaller f-number) and slowing the shutter speed (to, say, 1/125 or even 1/60 of a second).
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Blaker explained this in another book, Field Photography 1976:...at significant magnifications the choice of f-number is...nearly always a matter for compromise between depth of field needs and the resolution of fine detail in the image.
Depth of field, f-numbers and diffraction (or how to take a rotten photograph) AYDIN 2009
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Each "stop" is marked with its corresponding f-number, and represents a halving of the light intensity from the previous stop.
Further aspiration. 2006
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The literal interpretation of the f/N notation for f-number N is as an arithmetic expression for the effective aperture diameter (input pupil diameter), the focal length divided by the f-number: D = f/N. Noooo!!!
Further aspiration. 2006
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On a camera, the f-number is usually adjusted in discrete steps, known as f-stops.
Further aspiration. 2006
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To do this, choose a small aperture, which will be denoted by a larger f-number.
Macworld Ben Long 2010
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First, it's tempting to just dial in the largest f-number you can, but this is usually a bad idea.
Macworld Ben Long 2010
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In addition to considering focal length, pay attention to the "speed," or f-number, of your lens.
PCWorld 2010
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