Learn how to reduce the overall light output of a fixture.
There are a number of tools available to reduce either the overall light output from a light source, or to reduce the brightness on a particular part of the object you’re lighting. Most gaffers will choose a light source that is slightly larger than what is needed, then reduce the brightness using one of the methods listed below. This gives them flexibility should it become necessary to bright the light source – instead of taking the time to replace the light with a higher-wattage head, they can simple pull the scrims.
Wire scrims are circular metal meshes that, when placed in between the light and barndoors, reduce the overall brightness of the light. Every light has its own set of scrims and include:
Singles reduce light by ½ an f-stop
|Half Single Scrim
A single half scrim reduces the light by ½ an f-stop, but the wire mesh only covers half the open frame
Doubles reduce the light by 1 f-stop
|Half Double Scrim
A double half scrim reduces the light by 1 f-stop, but the wire mesh only covers half the open frame
Cutters are long narrow solids intended to block the top and bottom of a light source, allowing a grip to focus the light onto a subject. For example, when shooting a medium shot of an actor, use a bottom cutter to reduce the key light on the actor’s chest, and a top cutter to reduce the light off the top of the actor’s head to draw the audience’s attention to the actor’s face. Cutters are most commonly used in the following sizes: ·
10”x42” cutter, 18”x48” cutter, 24”x72” cutter
- Don’t overload the dimmer – Make sure the dimmer is rated for the wattage of the light you’re using. Dimmers on set are generally rated for 650 watts, 1000 watts or 2000 watts.
- Be aware of the color temperature change – The more you dim a tungsten light, the warmer the color temperature becomes. Although the effect is negligible when dimming up to 25%, further dimming will noticeably change the color of the light.
- Not every light can be dimmed – Dimmers are generally used on tungsten lights only. Kino-flos, HMIs, and other light sources requiring ballasts cannot be dimmed with traditional dimmers.
ND gels are applied over windows to reduce the brightness of the outside light without tinting it.
Once the gel has been measured, use a spray bottle of soap and water to help the ND gel adhere to the glass. Use a squeegee to eliminate any bubbles.