focal length

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an expression of the longest dimension of an object, or of the measurement between its two ends.
crown-heel length (CHL) the distance from the crown of the head to the heel in embryos, fetuses, and infants; the equivalent of standing height in older persons.
Measuring an infant's crown-heel length. From Lammon et al., 1996.
crown-rump length (CRL) the distance from the crown of the head to the breech in embryos, fetuses, and infants; the equivalent of sitting height in older subjects.
cycle length in cardiac pacing terminology, the time interval in milliseconds from one event to the next; it is the inverse of the intrinsic rate (beats per minute) or the paced rate (pulses per minute).
focal length the distance between a lens and an object from which all rays of light are brought to a focus.
Miller-Keane Encyclopedia and Dictionary of Medicine, Nursing, and Allied Health, Seventh Edition. © 2003 by Saunders, an imprint of Elsevier, Inc. All rights reserved.

focal length

In optics, the length from the lens to the point of focus of light rays passing through the lens.
See also: length
Medical Dictionary, © 2009 Farlex and Partners

length, focal

The linear distance separating the principal focal point (or focus) of an optical system from a point of reference (e.g. vertex, principal point, nodal point). The first (anterior) focal length is the distance from the lens (or first principal point) to the first principal focus. The second (posterior) focal length is the distance from the lens (or second principal point) to the second principal focus. Symbol: f.In a spherical mirror the focal length f, i.e. the distance between the focal point and the pole of the mirror, is equal to half its radius of curvature r
= r/2Syn. focal distance. See principal focus; mirror; cardinal points; principal points; equivalent power; refractive power; sign convention.
Millodot: Dictionary of Optometry and Visual Science, 7th edition. © 2009 Butterworth-Heinemann
References in periodicals archive ?
The Lumix lenses will also work perfectly on other MFT cameras, such as the Blackmagic Pocket Cinema Camera (BMPCC, if it ever ships) However, on the 16mm sensor of the BMPCC, there will be the crop factor to deal with.
Canon has two sizes of crop sensors, the 1.6x crop (APS-C) factor, on cameras like the EOS 550D and 7D (reviewed here), and a larger 1.3x crop factor also called an APS-H sensor, that is about as common as a solar eclipse.
Therefore a 50mm lens on a full frame camera would be equal to 50mm x 1.6 (the crop factor), which would be 80mm.
Fewer trees were damaged by maple leaftier in the cover crop treatments in the first yr, and there was no effect of insecticide on number of trees damaged, and no interaction between insecticide and cover crop factors (Tables 1, 3).
(12) During the growth and harvest of the lignocellulosic crop factors such as the fibre crop variety, soil conditions, climate, location, the section of the crop from which the fibres are extracted from and the harvest machinery used to harvest the crop also have an effect on the final properties of the lignocellulosic fibres.
Simulation modeling such as EPIC (Erosion Productivity Impact Calculator) (39) and Nitrogen-Tillage Residue Model (NTRM) (33) can be used to identify soil, climatic, and crop factors that limit crop production at specific sites.