// multi-utility computation suite · offline · instant · precise
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│ [c] calcalyst_ │
│ computation suite │
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photo.flash-guide-number Calculator
Calculates flash guide number, correct aperture for a given distance and ISO, or maximum flash range at a given aperture using the guide number formula (GN = aperture × distance). Guide numbers let you do manual flash without a light meter.
Inputs
Guide Number
Count of items or occurrences.
Aperture F
Reference formula or conversion factor shown for context.
Iso
Reference formula or conversion factor shown for context.
Target Distance M
Separation between two points or total path length. Check that units are consistent throughout the calculation.
Results
max distance at f/
The computed distance or separation.
GN at ISO
The value at the specified point or condition.
f-stop for
Reference formula or conversion factor shown for context.