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 ?
Figure 2 illustrates the basic structure of the proposed autofocus system.
For more information, please visit See3CAM_130 4K autofocus USB 3.0 camera.
Zhou, "An Induced Fluorescence Detecting System with Autofocus Electrically Tunable Len", IACSIT International Journal of Engineering and Technology, vol.
As shown in Figure 5, autofocus algorithm carries the preliminary focusing according to the surrounding environment, to narrow the autofocusing range.
Great depth of field, combined with highly refined autofocus technology, gives that video-centric handicam the advantage.
Also, the XF56mmF1.2 R APD is quick to use thanks to the high-speed, quiet autofocus. Without the shutter sound being a problem to the photographers, it's easy to capture natural shots of the subject.
It shoots at speed and delivers 20 frames per second in autofocus and up to 60 in fixed focus.
The camera has a high-performance Image Signal Processor (ISP) built-in that performs a variety of functions including 3A (Autofocus, Auto Exposure and Auto White Balance).
The FlowCAM imaging particle analysis system from Fluid Imaging Technologies is now available with an autofocus feature.
Our friends at Wikipedia say that the first autofocus single-lens reflex camera was the Polaroid SX-70 Sonar OneStep, released in 1978.
IDS Imaging Development Systems' uEye XS machine vision camera with autofocus measures 23 mm x 26.5 mm x 21.5 mm.
IDS Imaging Development Systems announced that it is shipping its new uEye XS, the world's smallest machine vision camera with autofocus. Measuring a compact 23 x 26.5 x 21.5 mm (.9" x 1.04" x .84"), the uEye XS is amazingly simple to integrate into virtually any imaging system, ranging from interactive kiosks and embedded systems using the Raspberry Pi, to traditional applications in medical technology, industrial quality control, microscopy, and access control.