Cinematographers need to understand another light measurement besides lumens, and that’s lux. Lux is the amount of light falling onto the subject or area you are illuminating. But before we focus on the significance of lux for video lighting, let’s first address lumens and how many you will need.
You’ll need about 3,000 lumens for video lighting for every 100 square feet you shoot. However, how many you need is not as critical as the light falling on your subject. While light source intensity is essential, depth of field and f-stop are just as powerful creative tools in lighting a video.
This article explains lumens in terms of video production, introduces you to the importance of lux and foot-candles, and advises on best lighting setups and practice to guarantee you create atmospheric lighting. Read on to discover all you need to light and shoot your video.
Understanding Lumens and Video Production
According to lighting powerhouse Arri Media, it is not the intensity of light that shines upon the subject but the instrument’s size that casts the light that has the most effect upon light quality. However, the amount of lumens your light casts should be proportional to the time of day and location in which your scene is set, as well as the look or style of the video.
As a rule, you’ll require more lumens for scenes that replicate natural, unadulterated sunlight or cover larger areas than you will for scenes set in small spaces with fewer actors.
So what should you be looking at, if not light intensity? What follows are additional factors you’ll need to consider.
The more intense your light source, the brighter it is. And when we’re looking at lighting for video, you need to appreciate what makes light quantity. Three factors affect the amount of light in a given situation. These are:
- Light intensity falling onto your area or subject that’s in the frame. We measure this in Lux or Foot-candles.
- The area you are lighting is measured in square feet or meters, depending on your imperial or metric preference.
- Distance between the scene you’re lighting and the source of lights. Light weakens across space. No matter the intensity of your light at its origin, the further your light is situated from a scene, the less intensely it falls upon the area you’re shooting.
Lowdown on Lux
Light intensity at the source corresponds to the amount of light and the light quality that falls upon the area you are filming. However, when you watch a cinematographer work, they place their light gauge at the points in the scene they want to highlight. They measure the lux then tweak the light source, aperture, and shutter speed to generate the desired effects.
In a scene that requires the effect of sunlight, your lights are replicating the sun’s output of 100,000 lumens per square meter. Imagine your scene area is one square meter; that’s a demand of 100,000 lux.
Basic Overview of Lumens and Lux According to Scene Type
Here’s a table outlining approximate lumens and lux requirements based on scene type. These are approximations, yet more than satisfactory for our needs.
|Type of lighting||Lux||F-stop at 1/50s||Area of 100 square feet|
|ISO 100||ISO 800||Lumens||Wattage|
|Partly cloudy sunny day||20,480||11||32||647,634||80,954|
|Office with Fluorescent lighting||320||1.4||4||10,119||1,265|
If vlogging from your smartphone is your thing, you won’t need such powerful lighting set-ups. Instead, opt for a ring light, use a reflector to maximize radiance and to soften shadows, and you’ll be well on the road to good lighting. The UBeesize Selfie Ring Light and the Neewer Light Reflector are good options.
Distance From Light Source and Diffusion
You may understand that you want 10,000 lumens to light your office scene and set yourself up with lights that deliver this power. However, remember that the distance you place those lights from the set will result in greater or weaker light landing on the area you plan to shoot.
What can you do to combat light diffusion? Light diffusion occurs naturally; rather than trying to fight it, the art of lighting for video is recognizing that every scene, setting, director, and style will require something different. Invest in a kit that will allow for versatility, such as the GVM Video Lighting Kit, then master the rudiments of lighting, and you’ll find yourself on the way to being a cinematographer.
Size of Light Source
Your light source’s size also affects the quantity of light that lands on the area you want to shoot. Large fluorescent bulbs that emit 1,600 lumens along their length will have less intense light output than a compact tungsten bulb of the same amount of lumens.
Once you’ve calculated the number of lumens you require and the type of bulb that produces 5,000 lumens, you’ll need to source a bulb capable of landing the amount of lux that you require cast on your scene. Manufacturer’s websites include this information (lux and lumens), so you can browse for a bulb that delivers the lux you want.
Optimum Lighting Setup for Your Video Production
For film lighting basics, the goal is to draw attention to the key areas or actors and balance the light with shade while creating a desirable and consistent look for your production.
Here’s our basic rule-of-thumb lighting setup that is a reliable method to light any scene.
Three-Point Lighting Setup for Your Video
To introduce you to the basics, first imagine that you have your actor sitting at the center of a clock, and the camera is placed at its circumference facing the actor. Around this dynamic, here is where and how to place the following lights:
- Key Light: A key light is the brightest of your lights and casts most of the light onto your actor. Imagine that it’s set a few degrees to the right of your camera lens. If the scene were a clock, the actor is at the center; the camera is placed at six; the key light is at four.
- Fill Light: Fill light is placed roughly equidistant from the camera as the key light is, which means it’s camera left. The purpose of the fill light is to remove hard shadows. Set your fill light at an intensity that’s lower than your key light. If your fill light is the same power as your key light, you’ll get a flat, exciting image.
- Backlight: A backlight will be set right of the camera, roughly opposite to your key light and, most significantly, behind your subject. Its purpose is to create a sense of depth, and it ensures your image has dimension.
Three-Point Lighting and Lumens
We decided it would be useful to look at the differences between energy-efficient and brighter LED lights compared to tungsten lighting. Here’s how the two compare in terms of watts and lumens:
With a 1,000-watt key light, a 500-watt fill light, and a 250-watt back light, your lighting is drawing 1,750 watts, which delivers around 21,000 lumens. Now, we don’t want you to overload your circuit, so let’s look at an LED alternative to this setup.
With LED, you gain 30 lumens per watt at its lowest tier, in which case you could apply a 400-watt key light, a 200-watt fill, and a 100-watt backlight and still produce the same intensity lumens at the source.
Check out whether ring lights or softbox lights are better here!
There are principles of lighting that remain consistent, no matter where you look or how you intend to light your scene. You can always adjust your camera settings to capture the aesthetic you desire, so adequate video lighting is not only about how many lumens. Still, it is also about developing your technique and craft.