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Guide number

When setting photoflash exposures, the guide number (GN) of photoflash devices (flashbulbs and electronic devices known as "studio strobes", "on-camera flashes", "electronic flashes", "flashes", "speedlights", and "speedlites") is a measure photographers can use to calculate either the required f-stop for any given flash-to-subject distance, or the…

History, Measurement & Standards

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Details

Lumen⋅secondsLuminous fluxSolid angleIlluminanceLux
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Understanding guide numbers

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Effect of shutter speeds

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History

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Overview

Understanding guide numbers

Details

Effect of power settings

Effect of flash angle (zoom setting)

Effect of filters

Effect of shutter speeds

History

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Guide number

Nodes46
Edges45
Triples90
Avg. degree1.96
Density0.043478
Components1

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Guide number

Top relations

related to External links · 13
Guide number → CalculatorScantips, Conley, EV, EV/Lux/FootCandle Conversion Chart Archived, Exposure Value, Flash Photography, History, ILFORDScantips, Memorabilia, Seaver, Sekonic, Understanding Flash Guide Numbers, Wayback Machine
related to With flashbulbs · 11
Guide number → At, Class, GE No, General Electric Synchro-Press No, If, ISO, Shutter, The GE No, The No, Vintage, With
related to Effect of filters · 8
Guide number → Even, Filters, Flash, For, However, Some, TTL, Unless
related to history · 8
Guide number → General Electric, In, London, No, Sashalite, Sashalite Limited, The, This
related to Units of measure · 8
Guide number → Another, As, Guide, In US, SI, Throughout, To, US
related to Effect of ISO sensitivity · 7
Guide number → Accordingly, Among, Guide, ISO, Such, To, Today
related to Effect of power settings · 7
Guide number → Full, GN, Moreover, Most, Nevertheless, Power, Reduced
related to Calculating with guide numbers · 6
Guide number → Alternatively, For, GN, It, Suppose, Thus
related to With electronic flash · 5
Guide number → Selecting, This, When, With, X-sync
related to Effect of flash angle (zoom setting) · 4
Guide number → Manufacturer, Many, Such, Virtually

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Important terminology

guide flash number numbers iso devices distance flashbulbs exposure camera shutter power table setting either manufacturers ft one light settings

Entity relationships Subject–Predicate–Object triples

SubjectPredicateObjectConfidenceSrc
feetinstance ofmanufacturers of flash devices typically provide foot-based guide numbers and add nomenclature0.80text
ftinstance ofmanufacturers of flash devices typically provide foot-based guide numbers and add nomenclature0.80text
or the foot symbolinstance ofmanufacturers of flash devices typically provide foot-based guide numbers and add nomenclature0.80text
these can make guide numbers misleadingly appear to be length-based units of measureinstance of30 m / 98 ft.Though nomenclature conventions0.80text
they serve as notations to eliminate ambiguity as to which length-based system of measurement underlies the guide numbers.Calculating with guide numbersIt is easy to use guide numbers to calculate either an aperture or a flash-to-subject distanceinstance of30 m / 98 ft.Though nomenclature conventions0.80text
they serve as notations to eliminate ambiguity as to which length-based system of measurement underlies the guide numbersinstance of30 m / 98 ft.Though nomenclature conventions0.80text
incandescentinstance ofFlash devices may come with detachable color-correction gels or filters to match the color of the flash with different types of ambient lighting0.80text
fluorescentinstance ofFlash devices may come with detachable color-correction gels or filters to match the color of the flash with different types of ambient lighting0.80text
off-center subjects with distant backgrounds or scenery with elements that have non-average reflectance can confound TTL meteringinstance ofnon-average scenery0.80text
the once-popular General Electric Synchro-Press Noinstance oflargely because even medium-size bulbs0.80text
Guide numberrelated to Calculating with guide numbersIt0.60section
Guide numberrelated to Calculating with guide numbersSuppose0.60section

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