sunny sixteen

A photographic light meter as a watch face. It reads the sky where you are and shows the exposure it would meter — ISO, aperture, shutter — in a 14-segment LCD.

There is no clock here. The triad comes from the Sunny 16 rule, bent by the real position of the sun and live weather at your location: bright midday sun meters near f11 at 1/ISO; overcast or dusk opens up and slows down. The same shared engine drives the Wear OS face, the Android widget, and this page, so every surface agrees on the sky.

The watch reads an ambient light sensor; a browser has none. So the readout runs the native default path — local time plus Open-Meteo weather — and the Light slider is an honest stand-in for the missing sensor: sweep it from bright sun toward night and watch the triad recompute. It sets luxOverride = 2.5 · 2^EV, the inverse of EV100 = log2(lux / 2.5). When weather or location fail, it falls back to exactly what the native face caches: ISO 400, f11, 1/50, RULE.

• Wear OS watch facebuilt
• Android home screen widgetbuilt
• Webyou are looking at it
• iOS widgetplanned
• Apple Watch complicationplanned