ND.3

Overview

"ND.3" in film lighting refers to a Neutral Density (ND) filter with an optical density of 0.3. It reduces the amount of light by exactly one f-stop without altering the color temperature or hue of the light. It is used as a filter sheet in front of luminaires, in filter frames, or on windows to dim the brightness without having to dim the lamp itself (which would shift its color temperature).

The notation ".3" signifies optical density and is the convention used in lighting technology (e.g., by Rosco and LEE). It should not be confused with camera ND filters, where the designation "ND3" may sometimes indicate three f-stops depending on the manufacturer. For lighting filters, the rule is: density 0.3 = one stop.

Technical Data

• Optical Density: 0.3
• Light Reduction: 1 f-stop (Stop)
• Transmission: approx. 50% (lets about half the light through)
• Effect: neutral gray, color-neutral (no shift in color temperature)
• Material: deeply dyed, heat-resistant polyester film
• Formats: filter sheets and rolls

The density scale is additive: each increase of 0.3 removes another f-stop and halves the transmitted light again.

On-Set Usage

ND.3 is the "smallest" commonly used increment in daily set operations and is employed when a luminaire is slightly too bright. Typical applications:

• Fine-tuning the light balance between multiple sources without dimming.
• Dulling windows to match incoming daylight to interior lighting (often combined with conversion gels).
• Reducing a highlight or a lamp that is just above the target exposure value.

Multiple ND gels can be stacked to add their densities (e.g., ND.3 + ND.6 = ND.9 = 3 stops). In practice, however, for greater reduction needs, one usually opts directly for the appropriate higher density to avoid reflection and handling losses. ND gels are also listed under their own catalog numbers by lighting brands (e.g., Rosco E-Colour 209 or Cinegel #3402 for density 0.3).