How to Calibrate Photone

By calibrating you can align Photone’s reading to a reference

Do You Need To Calibrate Photone?

Calibration is an advanced use case, requires some know-how, and is always optional. Make sure to have read our guide on how to measure accurately before continuing:

If calibrating makes sense depends on if your device already comes with a default calibration. Go to the app’s settings (⚙️-icon on the top right) and press “Calibrate Photone”. The screen will indicate if your device has a default calibration (look for the ✅-icon) or not (🟡-icon).

✅ Device With Default Calibration

Congratulations, your device comes with a default calibration. Calibration is not recommended. Use the calibration feature only, if you wish to align Photone’s measurements to a high-quality reference light meter. Read along to find out what makes a good reference.

🟡 Device Without Default Calibration

Your device does not come with a default calibration. Calibration is recommended, if you don’t measure what you expect and you have a reference you trust at hand. Read along to find out what makes a good reference.

How Calibration Works

By calibrating you align a meter’s reading to a reference. Let’s say Photone measures 1230 μmol/m²/s of PPFD under your grow light, but your friend’s high-quality PAR meter says 1270 which is 3.25% more. You can now calibrate Photone with your friend’s meter as a reference. This will adjust Photone’s measurement values by +3.25% making it read equally to the reference.

ℹ️

This process only works, if a meter measures linearly (meaning that e.g. doubling the light intensity results in double the measurement). But rest assured, unlike other light meter apps Photone is built to measure linearly on all supported devices.

What Makes a Good Calibration Reference

To calibrate, you need a reference in which you trust providing a measurement value for Photone to be aligned to. A reference could be either another light meter or a light source with a known intensity (e.g. as stated in a light output chart).

Reference Light- / PAR-Meter

You can use any high-quality light meter that is able to measure illuminance (lux or fc) or PPFD (μmol/m²/s) as a reference. You can also use another device running Photone.

⚠️

Beware of cheap light meters. We have tested many light meters and found that, as a rule of thumb, models costing less than $150 USD are awfully inaccurate, especially when measuring grow lights.

Multiple lux-meters under the same grow light showing significantly different values

Reference Light Output Chart

Most grow lights come with a spec sheet (see the example image below) that shows how much light intensity can be expected in a specific environment (e.g. a 2x2 ft grow tent), at a given distance (e.g. 12", 18", 24"), on a given point (e.g. center square) and power setting (e.g. usually full power unless noted otherwise). You can then use these parameters to calibrate Photone if you can replicate the manufacturer’s setup.

⚠️

Note that you’d need to exactly reproduce the setup chosen in the spec sheet and you need to trust your grow light’s manufacturer. We found that some manufacturers like to inflate their values provided on the spec sheets.

An example spec sheet indicating how much PPFD can be expected at a given distance

How To Calibrate

With a reference value at hand, calibration is fairly easy. First, make sure that your lamp is warmed up and its light output has become stable. Especially fluorescent (FL) or HID-lamps (HPS, CMH, MH) have a long warmup time of roughly 15 minutes. You can test if your lamp is stable by monitoring the current measurement value (it should remain equal over one minute). Then, follow the instructions the app’s instructions after having pressed “Calibrate Photone”.

Video Guides

To illustrate the calibration procedure, we've created the following videos showing the required steps for you:

Using a light output chart as a reference

Using a light meter as a reference

Using another device running Photone as a reference

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