February 11, 2014

The Art of Shaping Light: A Brief Guide to Using Flags to Add Contrast to Your Scene

Lighting is complicated, to say the very least. While there a numerous things that make lighting difficult, one of the most overwhelming aspects of lighting is just how many different tools there are. Without a practical knowledge of the various tools at your disposal and how to use them to sculpt light, your lighting can never reach its full potential. However, breaking the process down into small pieces and learning one tool at a time can make it far more manageable. Today, we'll look at one of the most underrated and under-utilized lighting tools, the flag.

Flags, also known as cutters, are pieces of thick black cloth, usually duvetyne, that are stretched over a metal frame. They are typically used to completely block light from falling onto a certain part of the frame, which is accomplished by manipulating the position of the flag in relation to the light by using a c-stand. Although flags have a staggering number of uses on a film set (courtesy flag, anyone?), there is one application that is absolutely crucial to effective cinema lighting: creating meaningful contrast within a scene.

Here's a video tutorial from Lights Film School, which also has a fantastic educational blog that's certainly worth perusing. In the video, they break down some of the best ways to use flags to increase contrast in your scene.

In this video, contrast is being added to the scene in two ways. First, one flag is being used to cut out light being cast onto the background by the key light, which is meant to light the actor. This is, by far, the most common use of flags on a set, although if you're short on flags or c-stands, barn doors can accomplish a similar effect (although I find flags to be the most versatile and effective method). The second way that contrast is being added to the scene is through flagging off just a small portion of the light on the actor's face, which creates a far more dramatic look than if the light was hitting him directly.

When using flags to block out light from a hard source, one of the most important things to consider is the distance between the light and the flag. If a flag is too far away from the source, it will create harsh, hard-edged shadows that will look unnatural and give away the placement of your sources. Unless you're going for an incredibly moody noir look, this is something that you should avoid. Instead, try to keep your flags within 8-ish feet of the source, so that the shadows from the edges of the flags are softer and less defined. This can create nice gradients of light that are extremely pleasing to the eye.

In addition to blocking out light directly from a source, flags have another wildly important use in film and video lighting, and that is to create negative fill.

Unlike the previous instance where flags were used to block direct light from falling onto a certain part of the scene, the process of using a negative fill is about subtracting ambient light in order to create contrast. Most often, negative fill is used in scenarios where natural light is in play. In these scenarios, it is often far easier and more convenient to subtract light from the scene than it is to add it. In order to control the amount of contrast that a negative fill provides, simply move the flag closer to the subject (for more contrast) or farther away.

Flags are an incredibly useful tool in the process of lighting for film and television, as they are one of the best ways to introduce thoughtful contrast into any scene. Through practicing and mastering the various flagging techniques discussed here, the effectiveness of your lighting will increase manifold.

What do you guys think about these flagging techniques? How have you used flags (or any light-blocking object) to better the lighting in your work? Let us know down in the comments!

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25 Comments

I watched the video but the only thing I took away from it was how bad Warp Stabilizer looks when you put it on everything in you timeline.

February 11, 2014 at 2:54PM, Edited September 4, 11:45AM

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Josh

Haha, my thoughts exactly.

February 11, 2014 at 3:49PM, Edited September 4, 11:45AM

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Spencer

+1

February 13, 2014 at 3:15PM, Edited September 4, 11:45AM

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Christian Anderson

Haha, straight up whack

February 19, 2014 at 7:56AM, Edited September 4, 11:45AM

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+1

February 23, 2014 at 4:36AM, Edited September 4, 11:45AM

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P337

Great tutorial. Looking forward to watching their other videos.

February 11, 2014 at 3:11PM, Edited September 4, 11:45AM

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The first example made me LOL. I was thinking, "you guys have heard of barn doors, right?"

February 11, 2014 at 3:47PM, Edited September 4, 11:45AM

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Nick

You do realize that barn doors are flags, but for the sake of a tutorial it's easier to show up what full flags are doing over little pieces of metal on a light, right?

Jesus, some people try to find any angle to hate.

February 11, 2014 at 10:03PM, Edited September 4, 11:45AM

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Tyler

+1

You can lead a horse to water but you can't make it drink. Some people seem to be allergic to useful information.

Although not necessary in every situation, I think flags. floppies and other dedicated light cutters and blockers (or their DIY equivalents) should be a part of everyone's lighting package. They offer the most flexible control and are what I believe help set great lighting apart from good lighting.

Hey NFS, comments no longer show up when i use my usual email. What gives?

February 12, 2014 at 7:30AM, Edited September 4, 11:45AM

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Brian

Ok, now move your barndoor 2 feet forwards.

Flags are an excellent tool on the set, you can't say that they work the same as barn doors just because they have the same main function. Your light source can even have a barn door and for many other pratical reasons, it's not the same. Open your mind and think about all the possibilities before criticize useful information people are sharing for free.

Those are excellent tips for a beginner and that's their function as I can see.

February 17, 2014 at 5:08AM, Edited September 4, 11:45AM

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I'm a bit confused. The flag blocking the key light from hitting the background is meant to remove that shadow that would otherwise be cast from the actor onto the background wall?

February 11, 2014 at 4:06PM, Edited September 4, 11:45AM

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Nick

You aren't confused at all. That's exactly what the flag is doing.

February 11, 2014 at 6:33PM, Edited September 4, 11:45AM

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Gavin

How does the flag being used to block the light from hitting the background not also block it from hitting the subject?

February 12, 2014 at 9:07AM, Edited September 4, 11:45AM

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Nick

They moved the subject further away from the background in order to create separation between the two (2:15). It's similar in concept to how you would ideally light a green screen (when you don't need the floor), where the screen gets its own, even light while the subject is moved far enough away to be lit separately to match the composited environment, or however you like.

It's also a factor of where the subject is in relation to the light source(s) and flags, where they're pointing and what the camera ultimately sees. At about :48, you see that some light the flags don't block is visible on the BG on the far right, which is okay because the camera won't be pointed over there. You could easily duplicate this tutorial with a flashlight, a few books (or boxes) and any suitably sized subject you have lying around to better understand how this works.

February 12, 2014 at 3:33PM, Edited September 4, 11:45AM

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Brian

exactly!

February 17, 2014 at 5:12AM, Edited September 4, 11:45AM

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Henrique

I've found that things like this really need to be learnt on-set. Even if you're just a PA, observe what the gaffer/DP is doing with the light. It always amazes me.

February 11, 2014 at 4:10PM, Edited September 4, 11:45AM

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Agreed, just watching a good gaffer or best boy for a day can be more educational than 4 years of film school.

February 11, 2014 at 5:43PM, Edited September 4, 11:45AM

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Robert Hardy
Founder of Filmmaker's Process
4283

Just think of all the time and money thousands of USC CSA graduates could have saved by simply spending a day on a set instead of wasting their time preparing for their Academy Awards.

March 17, 2017 at 12:15PM

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Zan Shin
250

You can re-correct the warp stabilizer. Have a few drinks and everything looks normal again.

February 11, 2014 at 7:33PM, Edited September 4, 11:45AM

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JPS

IMO, with lighting, it's easy to benefit from just doing. You can shoot anything with any camera - stills or video - and just adjust the positioning of your subjects and lights, add/subtract flags and cookies, up and down the dimmers, etc. Or you can watch the "Road to Perdition" again.

February 11, 2014 at 7:48PM, Edited September 4, 11:45AM

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DLD

Excellent tutorial. Looking forward to seeing many more educational posts like this. Great job Robert.

February 12, 2014 at 5:41AM, Edited September 4, 11:45AM

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Nigel

Lights Film School is amazing!

February 12, 2014 at 8:47AM, Edited September 4, 11:45AM

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Frank_P

I thought the tutorial was clear as what is happening until I tried it. It's inferred the falloff on the background light is created by the edge of the left flag. The falloff seen on a wall purely by using the edge of the flag is still fairly rapid and I don't think it looks like how light really is. What he fails to mention, is unless you cut the light source in half (flag is hitting the middle/hotspot) and closes/blocks off the rest of the light from there you won't get the pretty/natural inverse squared law falloff. If you want a more gradual falloff the light will need to placed at a sharper than 90 degree angle or change from tungsten to LED. I am going to rewatch this tutorial just to verify he omitted this info. Barn doors have many limitations with light spill being why they would not have demonstrated as clearly as the flags did here.

February 17, 2014 at 9:26AM, Edited September 4, 11:45AM

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Steve V

After re-watching the (first) Lights Film School tutorial I do believe that he is trying to show the edge/fall off on the background created just by the edge of the flag. For me it doesn't work very well and is inconsistent. I frequently get banding no matter what type of flag I use (Barndoor/black flag/black foam core). Banding is not "pleasing". Yes I know he was using a Zip light, but I tried it on the closest I have to a Zip light (a halogen shop light) and its there too. Its there with my Fresnels. Since there are no lighting diagrams, the tutorial is much harder to understand than it should be. I did find that a small amount of diffusion will pretty much eliminate the potential for banding, so maybe he just omitted that step. The whole concept of lighting both the background and talent/foreground with one light is appealing, but I think it could be a big hassle because the talent can only be in one location in relation to the light. Seems to me it would be generally easier to light talent separately from background.

February 17, 2014 at 10:31AM, Edited September 4, 11:45AM

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Steve V.

(I keep replying to myself). Ah but the purpose of the single light is to eliminate the shadow cast by the talent. So yes it can be done like the video shows, but like I said you have to be aware of the background falloff issue too. I find myself guessing because he did not clearly define the motivation of the key talent light nor did he clearly show the problem with the banding because he has a practical (which may have also reduced the banding).

February 17, 2014 at 10:38AM, Edited September 4, 11:45AM

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Steve V.