camera exposure calculator

how much light the camera actually needs.

photometrics calculator

load an ies file (optional)

choose .ies file

or just type numbers below — nothing is uploaded, the file is read in your browser.

units — applies to every panel below

throw geometry

trim height above target (ft)

horizontal distance (ft)

throw distance—

tilt from horizontal—

illuminance at throw

candela (cd)

throw distance (ft)

angled throw use geometry above

direct · footcandles—

direct · lux—

solve for candela

target footcandles

distance (ft)

candela required—

inverse square

illuminance at d1 (fc)

distance 1 (ft)

distance 2 (ft)

illuminance at d2—

lumens ↔ candela

beam angle (°)

lumens (lm)

candela (cd)

candela—

assumes all lumens inside the beam angle — real fixtures spill; treat as an estimate.

fixture stack

illuminance per fixture (fc)

fixtures overlapping

total—

additive only where beams fully overlap.

inverse square law runs everything: E = cd/d². everything else is geometry.

iso

shutter (1/x s)

f-stop

required illuminance—

in footcandles—

C=250 incident calibration — a starting point for broadcast lighting levels, not a meter.

about this calculator

give it the iso, shutter and f-stop camera is running and it returns the illuminance you have to put on the subject, in lux and in footcandles. it is the number to have in hand before anyone argues about whether the stage is bright enough for camera.

lux = 250 · N² · shutter denominator ÷ iso, on the C=250 incident calibration. that is a mid-grey starting point, not a light meter — skin sits above middle grey and the number moves with it.

shutter is not free light. it has to stay locked to frame rate and mains or you will chase led flicker all night. if you need more level, open the stop or add fixtures.

all the tools on one page →