focal ratio


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focal ratio

n
(Photography) photog another name for f-number
ThesaurusAntonymsRelated WordsSynonymsLegend:
Noun1.focal ratio - the ratio of the focal length to the diameter of a (camera) lens system
f number, stop number, speed
ratio - the relative magnitudes of two quantities (usually expressed as a quotient)
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References in periodicals archive ?
Increasing the focal ratio ("stopping down the lens") decreases the opening through which the light enters the camera and restricts the amount of light that's focused onto the image sensor.
Aperture for Camera
The optical bench measures focal ratio degradation (FRD) in specific optical fiber samples to determine if the fibers are appropriate for astronomy applications.
United States : Molex Implements Polymicro Technologies Optical Fiber Measurement System for Astronomy Applications
Another consideration is the focal ratio or 'speed' of the lens: f/1.
A modern video meteor detection system and network--overview and typical costs
The fibre uses a large core-to-clad ratio to reduce stress transfer to its core, maintaining laser beam quality and improving focal ratio degradation in lasers used for cutting, welding, drilling, soldering and marking.
High power optical fibres
Many spectroscopic applications require high performance optical fibres that transmit light over a broad spectrum and demonstrate minimal focal ratio degradation.
Pure silica optical fibre overcomes limitations
The focal length divided by the aperture is the focal ratio (the f/ number).
Astronomy photography: what to know: it used to be tough. But now, modern cameras and telescopes have opened up astrophotography to everyone. Interested? Here's where to start
The parameters are element spacing (d), focal ratio (g), lens width (G), and scan angle ([alpha]) (Figure 1).
Design and performance of a [K.sub.U]-band Rotman lens beamforming network for satellite systems
The focal ratio is considered critical because it holds expenses down by reducing the height of the building needed to house the telescope.
MOLDING SUCCESSFUL MIRROR PROJECT : ARIZONA CAST TO FASHION 40,000 POUNDS OF GLASS TO USE IN TELESCOPE
A two-stage concentrator works best if you have a moderately long focal ratio design, that is, where the focal length is substantially greater than the diameter of the aperture of the primary of the focusing mirror," said Joe O'Gallagher, a senior research associate and senior lecturer in the Physics Department at the University of Chicago and a colleague of Winston's since 1976.
Solar furnaces: concentrating 100,000 suns
Many spectroscopic applications require high performance optical fibers that transmit light over a broad spectrum and demonstrate minimal focal ratio degradation.
Polymicro FBPI Optical Fiber Delivers Industry-First Panoramic Spectrograph and Sensor Analysis
Modest vignetting of the field using the T-thread adapter was easily controlled with flat-field calibration at the relatively slow focal ratio of the instrument.
The QHY16200A CCD Camera: This camera offers a generous 16-megapixel field at an attractive price
And the focal ratio determines how long your exposure needs to be.
What to know before you buy: although they come in a bewildering range of sizes and shapes, all telescopes are variations on a few simple themes

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