📷 Flash Exposure Calculator
Leica-style manual flash exposure with GN₁₀₀, bounce, ambient and ceiling adjustments
Flash Library
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GN₁₀₀
is the Guide Number at ISO 100 (typically in meters)
Exposure Calculator
Direct Flash
Bounce Flash (2x distance)
Selected Flash
-- Choose a flash --
Fraction (1/64)
Percentage (50%)
Flash Power
Enter denominator (e.g., 64 for 1/64)
Ceiling Reflection Adjustment (stops)
-5.0
-4 2/3
-4 1/3
-4.0
-3 2/3
-3 1/3
-3.0
-2 2/3
-2 1/3
-2.0
-1 2/3
-1 1/3
-1.0
-2/3
-1/3
0 (baseline)
+1/3
+2/3
+1.0
+1 1/3
+1 2/3
+2.0
+2 1/3
+2 2/3
+3.0
+3 1/3
+3 2/3
+4.0
+4 1/3
+4 2/3
+5.0
Ambient Light Balance (stops)
-5.0
-4 2/3
-4 1/3
-4.0
-3 2/3
-3 1/3
-3.0
-2 2/3
-2 1/3
-2.0
-1 2/3
-1 1/3
-1.0
-2/3
-1/3
0 (flash only)
+1/3
+2/3
+1.0
+1 1/3
+1 2/3
+2.0
+2 1/3
+2 2/3
+3.0
+3 1/3
+3 2/3
+4.0
+4 1/3
+4 2/3
+5.0
Distance (m)
SOLVE
Aperture (f-stop)
SOLVE
Calculated Power Fraction
SOLVE
ISO
SOLVE
--
Formula:
ISO = 100 x ((distance x aperture) / (GN100 x sqrt(power_fraction / (2^(-ambient)))))^2 x 2^(-ceiling)
Leave ONE field blank to solve for it. Other three fields must have values.