Phone apps and light meters often report illuminance in lux. This calculator converts lux to exposure value (EV) and then to a shutter speed for your ISO and aperture, using the standard incident-meter calibration.
It's handy for planning night and twilight scenes, studio lighting and checking whether a scene will need a tripod.
How to use the Lux to Exposure Calculator
- Measure lux at the subject, pointing the sensor toward the camera.
- Choose ISO and aperture.
- Read the shutter speed.
How it works
EV₁₀₀ = log₂(lux ÷ 2.5) (incident calibration C ≈ 250). Shutter t = N² ÷ (2^EV × ISO/100).
FAQ
How many lux is daylight?
Direct sunlight is roughly 30,000–100,000 lux, overcast 1,000–10,000, civil twilight around 3–400, and a full moon about 0.1–0.3 lux.
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