Cine Essentials: Metering and Modifying Available Light
By Aimee Baldridge
Published by SekonicScheimpflüg Digital founder and production expert John Engstrom gives a step-by-step rundown of how to meter and modify available light on a cine shoot.
The classic image of a motion picture shoot features banks of super-bright lights and assistants unraveling giant skeins of electrical cable. But you don’t have to rent a generator to do a cine shoot these days, whether you’re working with a dedicated video camera or an HDSLR. In many cases, you can do it just with available natural light, especially when you’re working outdoors.
What’s still essential is knowing how to work with the light that’s there. To shoot professional-looking work, you need to be able to solve exposure problems, modify light to create a distinctive look, and keep it consistent over multiple shoot days and in different locations.
We asked John Engstrom
, founder of Scheimpflüg Digital
, to guide us through the process of metering and modifying available light for a cine shoot.
Tools and Information
You can use this equipment and information to measure and modify available light for a cine shoot:
- Light meter. For measuring ambient light, as well as bright and dark areas.
- Camera information. Find out which ISO, frame rate, and filters the director of photography (DP) wants to use during the shoot. If it’s a film shoot, find out the shutter angle.
- Light-related apps. These can include apps that provide weather predictions or tell you where the sun will be at any given time. If the sun will suddenly come out from behind a nearby building at 3:00 p.m., it’s good to know that in advance. Engstrom uses the Helios sun position calculator app.
- Tape. Gaffer’s tape can come in handy for securing modifiers.
- Stands. You’ll need something to hold your modifiers up. It can be a light stand, a C-stand, or your trusty assistant. Different types of modifiers will require different supports. Make sure you have the right supports for all your modifiers.
- Sandbags. To weigh down the stands so that they don’t fall over, especially in the wind.
- Clamps. It’s always good to have a few clamps handy, for attaching modifiers to stationary objects and stands.
- Modifiers. Anything that changes the way the light falls is a modifier. It can be something that shapes the light or changes its direction, or it can be something that increases or decreases its intensity. Let’s take a look at the main types of modifiers you can use with available light:
- Diffusers. A diffuser is anything that’s positioned between your subject and your light source in order to make the light softer and less directional. Diffusers also reduce the intensity of light.
Common diffusers for filmmaking include silks, scrims, nets, and grid cloths. Silks come in different weights, which determine how much they reduce the intensity of the light. Diffusers that let some light through, like grid cloths, will reduce intensity less and provide a more directional light. Diffusion cloths are usually stretched on a metal frame. Smaller diffusers are often collapsible discs.
To tone down hot spots or make lighting more even, you can use a large diffuser overhead or to one side of the scene. This is especially useful on very sunny days, when strong, directional sunlight can create harsh shadows and high light ratios on your subjects.
- Reflectors. There are times when you might want to add more light, either to fill a shadow side and even out the lighting ratio, or to give a little more snap to flat lighting on an overcast day.
You can use any white or metallic surface as a reflector. Just be aware that any coloring in the reflective material will create a color cast in the light. That includes metallic surfaces that aren’t silver. Using a metallic surface will also create more specular highlights on the subject, while the light from a plain white reflector will be softer.
Common reflectors used in filmmaking include panels and reflective fabrics stretched on frames, as well as smaller cards and collapsible discs.
- Flags. If you’re dealing with an extreme available light ratio or an unwanted hot spot, you may need to completely block the light. Anything that blocks the light is called a “flag.” It’s usually made of a flat black material, so that it doesn’t reflect any light or add a color cast to the scene.
Another use for black surfaces as modifiers is to create negative fill. Just as you would set up a reflector to bounce fill light into a shadow area to make it brighter, you can set up a black surface to prevent light from bouncing onto an area to make it darker.
Common materials used as flags in filmmaking are black panels and Duvetyne.
John Engstrom: “The DPs are the ones who decide whether we should diffuse or add light, or whether they want the light to look really harsh with deep shadows. Sometimes we’ll just shoot in bright sunlight, and half the face will fall in shadow. It depends on the look the DP wants to achieve.
What I find most difficult is when there’s very bright sun and they want it to look soft. That’s a hard thing to accomplish. Usually we try to expose for the highlights and use modifiers to bring light into the shadows."
Meter the scene.
Once you have your camera and props in place and have marked out your subject positions, you can meter your scene. Your goal is to evaluate light levels so that you can modify them to control the look of the work, ensure that everything in the scene falls within the latitude of the camera, and make notes on the lighting so that you can replicate it.
Here’s what to do:
- Set your meter to Incident Mode. Make sure the dome on your meter is not retracted.
- Set your meter to the ISO you’re using for the shoot. You should use the same ISO setting for scenes that you want to have the same look, since visual noise increases as you increase the ISO or gain.
- If you’re using a cine meter, set the frames per second you’ll be shooting at.
- If you’re shooting on film and using a shutter angle other than 180 degrees, use a cine meter that lets you set the shutter angle.
- Stand in the spot where the subject is going to be.
- Aim your meter’s dome at the camera and take a reading.
- If direct light is hitting you, aim your meter directly at it and take another reading.
- If there’s a shadow falling on one side of you, aim your meter in that direction and take a reading.
- Make a note of all of your meter readings. Now you know what the lighting ratio on your subject is. In other words, you know what the difference in exposure between the highlight side and the shadow side is, measured in f-stops. (You can learn more about lighting ratios here.)
Modify the light.
If the lighting ratio on your subject doesn’t create the look you want, you can use the information you’ve gathered with your meter to modify the ratio. Once you know what the ratio is, you have a quantifiable way to approach controlling contrast.
Modifiers will let you craft the lighting look you want from the available light and fix areas that are under- or overexposed. When you get the look you want, make sure to re-meter and make a note of the new readings so that you can replicate the look in another location or at another time.
As you’re evaluating your scene and modifying the light, here’s what to check:
- Camera latitude. Make sure that everything in the scene falls within your camera’s exposure latitude. Otherwise, areas will be blown out to white or appear as black patches with no detail.
A camera’s latitude is the range of brightness values it can record in a scene, from bright highlights to deep shadows. (Photographers usually call it “dynamic range” instead of “latitude.”) Latitude is usually described in exposure stops. For example, reviewers have found that the Canon 5D Mark II has a latitude of about 10 stops in video mode at its lowest ISO settings. (Latitude decreases at higher ISO settings.) If you meter your scene and find that there are more than 10 stops’ difference in exposure between the brightest and darkest areas, some elements in the scene will be recorded with no detail, as pure white or black.
Some cameras have more latitude than others. Do a little research and find out what your camera’s latitude is before the shoot. Check professional reviews from magazines and Web sites to find this information.
- Dark areas. Look for spots in the scene that are noticeably dark. They may be caused by shadows, dark surface colors, or just uneven natural light. Even if they’re within your camera’s latitude and show some detail, they may be too dark to correspond with the look of the whole scene.
For example, if your whole scene has relatively low contrast, but there’s a dark object in one corner that looks like a featureless blob, it will be distracting and detract from the look of the scene. Use reflectors to bounce light into dark areas. You can think of them the same way you would think of a fill light that you use to fill shadows.
- Hot spots. Spots that are too bright can be as distracting as ones that are too dark, often more so. Make sure you look up when you’re looking for hot spots—at the tops of people’s heads and anything else that might be first in line to get hit by incoming light beams. Use diffusers and flags to bring the illumination level down in hot spots.
- Catchlights. Make sure there’s some kind of reflection in your subjects’ eyes, however slight. Without these catchlights, eyes look lifeless. In some situations, you can use a small silver card near the lens to bounce a reflection into the eyes. Other setups may require different placement of a reflector.
- Facial structure. When you set your exposure to retain detail in the highlights, you can lose all detail on the shadow side of your subject’s face and in the eye sockets. Use reflectors to bounce light back into these areas. This can also help create catchlights in the eyes.
If the light is too flat to show the contours of the face, you can use negative fill to bring them out. When you set up a flag on one side of your subject, the light striking the flag will be absorbed instead of bouncing onto the person’s face, and that side of the face will have more shadow to create contour.
- Motivation. Not your crew’s motivation. The light’s. “Motivated” light is light that comes from a place that makes sense in the scene. If your main light is sunlight coming from one direction, make sure any light you bounce into the scene with modifiers looks like it’s coming from that source as well, or from another plausible source in the scene. Adding a bright light coming from a different direction can look unnatural.
- Sound. Ever sit on the deck of a sailboat and listen to the sound of a sail flapping in a light wind? If you don’t want that sound in your footage, make sure you don’t set up a big fabric modifier where the wind will hit it. Some modifier cloths come in “silent” versions that are designed not to make noise in the wind. To reduce the amount of noise with any fabric, make sure it’s pulled tight when you secure it to a frame.
John Engstrom: “I want people to look natural, and have detail in the eye sockets and the structure of the face, so that’s what I’m trying to fill. I’m careful not to leave a black spot in the middle of the face. I try to wrap the main light, filling between the highlight and the shadow, rather than filling into the deep shadow. You don’t want to get a bright spot on one side of someone’s face and a subtle bright spot on the other, and then a deep, dark area in between.”
When you’re metering the available light in a scene, you should use incident mode to get accurate results. There’s one exception to this: metering reflections. When you have reflective surfaces in a scene, you should meter them directly in spot metering mode, from the camera position. Look around your scene for objects like cars, windows, and glasses. You can read more about metering and modifying reflections here.
Handle changing light.
Available light is usually natural light, and natural light changes. Your shoot may last more than one day, and you may move to multiple locations where you need to maintain the same look. All of these factors are reasons why it’s important to meter your light and keep notes on your readings. That way, you can adjust your modifiers and camera settings as the light changes, to maintain a consistent look.
After you’ve set up your modifiers and taken your initial meter readings, there are a few things you should do over the course of the shoot:
- Re-meter periodically. If the light looks like it’s changing more than what would look natural as clouds go by, take another meter reading. Engstrom picks a neutral object in the scene to spot meter periodically in order to see how much the general light level is changing over time.
- Adjust exposure as needed. When the general light level changes more than a stop, let whoever is running the camera know so that they can make any necessary changes to the exposure settings. If you’re operating the camera yourself, consider bringing your exposure up or down if you’re trying to maintain continuity with an earlier scene.
- Monitor the quality of light. Differences in specularity and directionality of the light are often more important than changes in the quantity of light, because they change the way shadows fall and the overall look of the image.
If a cloudy sky clears and there’s suddenly bright sunlight, your scene can take on a whole new feel. When you see changes like that happening, re-meter the shadow and highlight sides of your subject to make sure the ratio is still close to the initial ratio. If it’s not, adjust your modifiers to keep the ratios, and the look, consistent.
John Engstrom: “Sometimes we’ll want scenes to look similar and we aren’t shooting everything on the same day. But it’s going to have to look like the same day, no matter what. So I definitely take good notes on what the ratios are and what the light looks like, because one day it could be sunny and the next partly cloudy, and you’re going to have to make it look the same somehow.”
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