Light Meter・Lux Meter1.4 - App Store

LUX METER - LIGHT LEVELS IN LUX AND FOOT-CANDLES

Lux Meter is a camera-based light meter for illuminance. Aim the rear camera at a surface and read the level in lux and foot-candles, plus EV at ISO 100 - desk lighting, a grow light over houseplants, a scene for an analog camera.

WHY THE NUMBER IS WORTH TRUSTING

▸ Metering method always on screen: Reflected . Point AE or Reflected . Center.
▸ Readiness comes from a 1.2-second EV window: 6 valid samples over 650 ms within a 0.16 EV spread to lock, then a 0.28 EV hysteresis against flicker.
▸ No fresh frame for 2 seconds reads Stale; unusable metadata reads Error.
▸ Moving the target, changing zoom or lens, returning from background or recalibrating restarts the window.
▸ Nothing saves or samples until the reading is valid and stable.

ROOM AND WORKPLACE LIGHT LEVELS

Pick the space or task, then run the five-point survey: five samples across the working plane, each held until stable, giving average, minimum, target range, observed min/average uniformity and the sampling grid.

15 practical targets in 5 groups: general office 300-500 lx, detailed office work 500-750, precision factory 750-1000, warehouse and hospital ward 100-200, corridor 100-150, classroom 300-500, library 500+, operating room 1000+, bedroom 50-150, plus kitchen, bathroom, garage, retail floor and restaurant - practical guidance, never legal certification.

GROW LIGHTS, PPFD AND DLI FOR PLANTS

Measure at the leaf plane of one plant and decide for that plant: pick the plant, the light source and the photoperiod, and the reading becomes a PPFD and DLI estimate in mol/m²/day.

16 plants carry daily targets: pothos and snake plant 2-4, ZZ plant 1-3, peace lily 3-6, monstera and philodendron 4-8, fern 4-7, rubber plant 5-10, fiddle leaf fig 8-12, plus bird of paradise, succulent, herbs, tomato, pepper, lettuce and strawberry. 5 light sources: sunlight, white LED, fluorescent, HPS, metal halide. The sample log marks periods it did not cover, so a thin number never passes for a full day.

EXPOSURE FOR PHOTO AND VIDEO

The same reading solves exposure: aperture priority, shutter priority and manual across f/1.0-f/64, 1/8000 s-60 s and ISO 25-12800 in full, 1/2 or ⅓ stops. Each solution gives the exact result, the nearest setting your gear really has and the residual error in stops - out of range, by how many. Manual shows Over / Matched / Under on a ±3-stop scale, and Cine turns FPS, shutter angle, ISO/EI and ND into an equivalent shutter and f-number.

RECORDS AND CSV EXPORT

Readings, surveys, DLI estimates, comparisons and monitoring all land in one history list - each with its method, readiness state, calibration and mode inputs. Page the archive, export to CSV.

ALSO INSIDE

▸ Lock a reading; switch lux ↔ foot-candles in one tap
▸ Lux reference - 16 environments, 0.1 lx full moon to 130,000 lx direct sun
▸ EV reference - 11 scenes, -6 EV starlight to +18 EV snow
▸ A/B comparison - capture A, move to B, get the EV difference and brightness ratio
▸ Continuous monitoring - min / avg / max trend, real sampling interval, samples and missed samples, markers; background time logs as a gap
▸ Guided calibration - enter a reference value, aim at a uniform surface, wait for stable, apply the offset

LIMITS AND PRIVACY

A reflected-light estimate from camera exposure metadata - not an incident meter, not a PAR sensor, not a certified laboratory instrument - so it depends on the surface you aim at. The camera only measures light: no photos taken or stored, nothing uploaded, no account, and readings leave your device only in a CSV you export.

Free covers the live reading and its readiness state; Pro removes ads and unlocks every workflow.

Point, wait for stable, read the number - and stop guessing how much light really reaches that desk or that leaf.

Terms of Use: https://zeroplay.io/docs/legal/terms-of-service

Privacy Policy: https://zeroplay.io/docs/legal/privacy-policy

Version History Bug fixes and performance improvements for a smoother experience. 1.4 Aug 8 Bug fixes and performance improvements for a smoother experience. 1.3 Jul 13 Bug fixes and performance improvements for a smoother experience. 1.2 Jul 6 Bug fixes and performance improvements for a smoother experience. 1.1 Apr 21 1.0 Mar 21