How to measure light in closed or confined spaces

Last Update: Jan 10, 2026

The Photone app for Apple Watch allows light measurement in closed or confined spaces like grow tents, aquariums or where ever you need to measure.

Light measurements in closed or confined spaces like grow tents, aquariums, or tight corners can be tricky. Ideally, you’d want to remove yourself from the environment to avoid interfering with the results. Your presence will skew the accuracy of your readings because you cast a shadow and will be blocking reflections.

If only there was a way to read light measurements remotely …

Introducing Photone for Apple Watch

Now, there is! Whether you’re a hobbyist grower, a professional cultivator, or just someone passionate about perfecting your plants’ lighting, Photone’s new Apple Watch feature is designed to streamline your workflow and give you more flexibility than ever before.

Simply remove yourself from the scene, leave your phone as the measurement probe and read the current measurement from your wrist. This allows you to:

Take measurements with your hands free to take notes or adjust lighting
Fully close your grow tent for the measurement
Easily measure at hard to reach spots or areas
Show off to your friends because that’s something their light meter can’t do

How It Works

Getting started is simple:

Install Photone on your Apple Watch (requires watchOS 26)
Open Photone on your iPhone and start measuring
The readings will automatically appear on your watch — no extra steps needed!

Swipe on your watch or iPhone to switch between different measurements (PAR, DLI, lux, etc.). To hold a measurement, just tap the screen on your watch. This automatically activates the "Latching Hold Mode" on your iPhone, so your HOLD-state stays synced across both devices.

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This feature is exclusively available for Photone Pro users.