Why my lux differs from a light meter
Meter works lux out from the camera's exposure, assuming the surface it reads is 18% gray. On a gray card filling the frame it is close; anywhere else it is an estimate, and it is no incident reading.
Step by step
- Switch to GRAY CARD.
- Hold an 18% gray card where the subject is and fill the frame with it.
- Read the lux, or foot-candles if you picked them in Settings.
If that didn't work
A white wall reads high and a dark room reads low, because they reflect more or less than gray. For lighting ratios, an incident light meter is still the tool; Meter's Stops option shows the key-to-fill difference between two readings.