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Choosing The Correct Light Source Setting

Learn which setting to choose to get accurate light intensity measurements

Photone requires you to select the light source when measuring light intensity. This allows the measurement algorithm to correct the spectral error and thus produce accurate results. This guide helps you choosing the right setting depending on what kind of light you’re measuring.

Natural Daylight / Sunlight

You might know that the sun’s light (i.e. its spectrum) will change during the day. The light is colder (more bluish) during the day and warmer (more reddish) towards sunrise and sunset. You might also know that windows block UV light and thus sunlight is different indoors compared to outdoors. However, these variations have a negligible effect on the measurement result.

Choose the “Sun” setting whenever you're measuring natural sunlight/daylight, whether in direct light or shade.

LED Grow Lights

Light Emitting Diodes (LEDs) are the most popular and energy-efficient choice when it comes to artificial lighting for any kind of farming. Photone separates between five different kinds of LED assemblies.

Choose “LED Full Spectrum” if your LEDs are white/yellowish or if your lamp consists of RGB LEDs emitting white light. This setting covers all white LEDs reaching from warm (~3000K) up to cool (~6500K).

Choose “LED Full Spectrum + Red” if your lamp contains mainly white/yellowish LEDs with some additional red (~660 nm) LEDs. This is common for high efficiency grow lights.

Choose “LED Red / Blue” if your lamp emits purple light and mainly contains red and blue LEDs.

Choose “LED Blue / White” if your lamp emits cold white light and has blue LEDs among the whites. These lamps are commonly used for aquariums.

Choose “LED Deep Red” if your lamp uses only red LEDs (~660 nm). These lamps are often marketed as "deep red spectrum" or "red spectrum supplemental lights" and are commonly used as boosters during flowering stages. If your LED lamp emits white light and just includes some additional red LEDs that cannot be turned on independently, select “LED Full Spectrum + Red” instead.

Fluorescent Lamps (FL)

Fluorescent lamps usually come in two forms: either in fluorescent tubes with sockets like T5, T8, T12 etc. or as compact fluorescent lamps (CFL) with sockets like E27, E40, etc. What form or socket your lamp has doesn’t matter. However, what’s important for choosing the right setting is the emitted spectrum.

Choose “FL Warm” your fluorescent lamp emits a warm, yellowish light (~3000K).

Choose “FL Daylight” if your fluorescent lamp emits a cold, white light (~6500K).

Choose “FL Blue” if your fluorescent lamp emits a bluish light (~10000K or more).

Choose “FL Actinic” if your fluorescent lamp emits a purple light or is labeled as “actinic”. These lamps are usually used as supplemental lighting in aquariums.

High Intensity Discharge (HID) Lamps

The most common HID lamps used for grow lighting are High Pressure Sodium (HPS), Metal Halide (MH) or Ceramic Metal Halide (CMH) bulbs. They come with two different types of connectors: either a threaded socket (e.g. E40) or a double ended connector. The connector type is irrelevant for the light source setting selection.

MH and CMH bulbs exist in different color temperatures (denoted in Kelvin). Just like the connector type, this is also irrelevant when picking the right setting. Important is only the type of HID lamp you’re using.

Choose “HPS” if you have a High Pressure Sodium (HPS) lamp.

Choose “CMH” if you have a Ceramic Metal Halide (CMH) lamp.

Choose “MH” if you have a Metal Halide (MH) lamp.

Incandescent Lamps

Incandescent lamps come in several varieties, including standard bulbs which were once ubiquitous for home lighting, halogen lamps, and special types like krypton/xenon each with slight variations in efficiency, lifespan, and light quality. These lamps can be recognized by their characteristic warm glow and high heat output, the latter making them less efficient and thus not recommended for grow lighting.

Still they’re used in various applications such as stage lighting, heat lamps, vintage-style decorative lighting, cars and home appliances. Despite their differences, all incandescent lamps operate on the same basic principle of heating a filament in a gas filled bulb to produce light.

Choose “Inc.” for any kind of incandescent lamp.

Measuring Multiple Different Light Sources

If you wish to measure the combined light intensity of multiple light sources of a different type, measure each light source type individually using the corresponding setting. Then sum up the measurements to get the resulting total light intensity.

Unsure Which Setting to Choose?

Check your lamp's socket, bulb, packaging, specification sheet or the manufacturer's website — it should state what kind of technology it uses to produce light. For LEDs you can also just look at the individual chips and their color.

If still unsure, reach out to our support and provide as much information as possible about your lamp. We’re happy to help!