Reducing LED Spotlight Intensity with Neutral-Density (ND) Gels

led spotlight

Reducing LED Spotlight Intensity

Illuminating small spaces with bright lights can cause glare and unwanted blinding to occur. In studios and for lighting systems without dimmable features, operators may install accessories over the luminary to reduce brightness.

One of these accessories is called a neutral-density or ND filter. This lighting accessory typically comes in the following grades: 0.3 (ND3), 0.6 (ND6) and 0.9 (ND9). When used correctly, ND gels can improve lighting quality for the entire space – resulting in diffused effects.

Light Intensity vs Color Temperature

LED spotlights are known for their tight, powerful beams. When incorporated with other types of luminaries, the light could overpower other beams in the location. As a result, illumination could appear uneven. Operators may cover an LED spotlight with an ND gel, so that it does not ruin the illuminative characteristics of the entire lighting system.

Modern ND filters are constructed of colored sheets of polyester. Previously, the accessories were made out of dried gelatin. The issue with low-quality, gelatin-based ND gels is their tendency to melt when exposed to high temperatures. For mounting close to theatrical spotlights, this type of ND filter is not recommended.

Benefits and Applications

It is important to clarify that ND light gels are very effective in controlling light intensity – not color temperature. In application, an ND filter can be applied over a window, in order to reduce the intensity levels of natural sunlight entering the location.

An ND gel may have varying grades of filtering on the surface to accommodate partial dampening of the light beam. For example, when filming in extremely bright outdoor locations, an ND layer with a slightly darker tint in the upper section could actively filter sunny skies while allowing more light to pass in the lower section of the filter. This type of filtering accessory is called a graduated ND gel.