Flags, an Introduction...

Flags are similar in function to Barn Doors, however with a notable exception. They tend not to be attached directly to the light. They come in a range of sizes from a sheet of paper to around four by eight feet.

Their purpose is to keep light from a fixture away from areas that you don't want it to light. Areas of your set aren't the only things to benefit from use of a flag.

flag mounted to tota
Tota-flag with Flexi-shaft mounted on Tota-light with umbrella

no cookie
Flag keeps stray light from hitting camera lens
Click & Hold image to see un-flagged version

flag background
Flag trims light spill from background
Click & Hold image to see un-flagged version

Flags block light from spilling onto things that you don't want lit. But since flags are only blocking part of a beam, there will be a shadow line to deal with. How sharp this shadow line will be depends on the size of the flag, the sharpness of the light (how hard or soft), and the distance from the flag to the shadow.

Whenever you are using an opaque object to block light from striking something in whole or in part, you are flagging the light. As much consideration to cutting and controlling unwanted light should be given as there is to applying light.

Flags are most often used with a separate stand but in practice can be mounted almost anywhere. Barndoors block light by interrupting the beam from the outside edges only. While a flag often does it that way too, it can also take a piece from the center of the beam or control of portion of it with a unique shape in area and leaving the rest of the beam untouched.

Mounting the flags on a separate stand also allows a greater degree of control than the light's barndoor, by being able to adjust the distance of the flag between the light and the surfaces the shadow of the flag falls on.

When you move a flag away from a light source and closer to a wall for instance, you will notice the edges of the flag's shadow become more defined. As you move the flag closer to the light, the edges of the shadow will progressively blur; sometimes to the point of being unperceivable.

The size of the flag in relation to the light also needs to be considered. Flagging small hard light sources is fairly easy since it is a more defined beam. The light from a large diffuse light source will have a tendency to wrap around a smaller flag.

Commercially, flags are available in sizes from about the size of a sheet of paper to four feet across. Elongated rectangular flags are sometimes referred to as Cutters. In still photography you might hear flagging devices called Gobos.

Smaller flags have names like Fingers (rectangular) and Dots (circular). These are often constructed as needed with pieces of matte board and stiff wire.

flag position
Flag flag positioned to remove center of light beam
flag position
(left) flag further from wall = blurrier shadow
(right) flag closer to wall = sharper shadow

orange dot
Some Practical Uses for Flags
Flagging isn't limited to controlling the light that is directed at your subject. Much like using your hand to shade your eyes, a small flag is often used to keep a light from flaring the lens (French flag) or interfering with the camera operator's vision (Courtesy flag). Look for hair or back lights to be the first offenders.

They are also used:
  • To remove the center of the beam of a backlight, allowing it to light the subjects shoulders while not over exposing a balding or light haired head.

  • To reduce the amount of light falling on a white shirt, to help keep levels within the camera or film's contrast range.

  • To control the spill of one or more lights to reduce the brightness of the background and allow the subject to be brighter and the focus of attention.

  • To block the direct reflection of a light in a shiny surface, such as glassware.

  • As negative fill, to reduce the stray bounced light from a nearby white wall which is causing your lighting to look flat. Common in tiny offices.
© 2008 Lowel-Light Mfg. All Rights Reserved.