Full Spectrum

Overview

"Full Spectrum" in film lighting refers not to a specific lamp, device, or manufacturer code, but to a quality characteristic of a source's light spectrum. It denotes light that covers the entire visible wavelength range – roughly from blue/violet through green and yellow to red – as continuously as possible and without significant gaps or peaks. The reference points are classic continuous emitters: daylight (sun) and the glowing tungsten filament of a tungsten lamp.

Important: The term is not technically standardized. There is no official threshold above which a light is considered "Full Spectrum" – the term originally stems from marketing and qualitatively describes the naturalness of the spectral distribution. The actual spectral quality is therefore quantified using metrics like CRI, TLCI, and SSI (see below), not by the label itself.

Why it Matters on Set

The counterpart to full spectrum are "broken-spectrum" sources with pronounced peaks and gaps in the spectrum: simple RGB LEDs, older fluorescent tubes, or discharge lamps. Such sources may appear white to the eye but render certain object colors incorrectly – particularly critical for skin tones, as skin transmits light into deeper tissue layers and reflects it back colored. If, for example, the deep red component (R9) is missing from the spectrum, skin will appear pale or lifeless on camera and will be difficult to correct in grading.

Modern professional luminaires therefore produce full-spectrum light not with pure RGB, but with multi-emitter engines that mix several LED colors to fill spectral gaps – such as RGBWW (RGB plus warm and cool white) or systems with additional colors like amber, cyan, or lime. The ARRI Orbiter, for instance, uses a six-color engine (red, green, blue, amber, cyan, lime) to maintain high color fidelity across the entire CCT range. Such engines deliver high CRI/TLCI values and more uniform spectral coverage than pure RGB or RGBW solutions.

Measuring Spectral Quality

Since "Full Spectrum" itself is not measurable, the spectral quality of a source is assessed using standardized indices:

SSI in particular is closely linked to the concept of full spectrum: it compares the actual spectrum of a light to that of an ideal continuous emitter, thus directly showing how close an LED is to "true" full-spectrum light.

Use on Set

When purchasing or renting equipment, one should not rely solely on the marketing label "Full Spectrum" but should pay attention to the published CRI, TLCI, and ideally SSI values – preferably across multiple color temperatures, as the spectral quality of many mixed-light engines fluctuates with the set CCT. As an example of current full-spectrum-capable devices, ARRI mentions the Omnibar with values of CRI 98 / TLCI 98 at 5600 K.

Rule of thumb: Daylight, tungsten, and high-quality mixed-light LEDs provide full-spectrum, skin-friendly light; pure RGB effect lamps and old fluorescent sources, on the other hand, should be treated with caution for close-ups on faces.