In this guide, we’ll break down three key ways to use an incident light meter: for exposure, contrast levels, and tighter contrast levels or flat surfaces.
A warning: You’ll find many kinds of advice on this subject online. Some may be contrary to what I’m saying, so take this as my way to use a light meter. If it doesn’t work out, feel free to find another way.
First, here’s the video on how to use a light meter:
Whether you’re lighting a scene for a film, commercial, or any other project, knowing how to read light accurately can make a huge difference in the quality of your shots.
For cinematographers, understanding how to properly use a light meter is crucial. To know why, read this article:
An incident light meter measures the light that falls on a subject. Most cinematographers prefer incident meters because they give a more direct reading of the light, helping you manage your lighting more efficiently.
Now, let’s dive into the three ways you can use this tool.
1. Using a Light Meter for Exposure
One of the uses of a light meter is to get an accurate exposure reading.
However, modern digital cameras have different settings, presets, and built-in tools that do a far better job at helping with exposure. That’s why I don’t rely solely on an incident meter for exposure anymore. It’s not as consistent or as quick.
Better Alternatives for Exposure:
- False Color: This is my preferred tool for exposure. A False Color maps different colors onto your image based on exposure levels. It’s an easy way to see which areas are overexposed or underexposed.
- Waveform Monitor: My second favorite tool. It shows you a graphical representation of the light in your image, giving you a precise look at where your highlights and shadows fall.
- In-Camera Meter: Most digital cameras have a built-in exposure meter that can give you a quick estimate of the overall brightness in your frame. It’s a helpful guide, but not always useful to match shots.
- Zebras: These are diagonal lines that appear on overexposed areas in your viewfinder. They’re a fast way to spot problem areas in your exposure. They’re useful, and I still use them, though the false color tool is definitely better.
To know more about exposure tools for video, watch this video:
2. Using a Light Meter for Measure Contrast Ratios
The second way you can use an incident light meter is to measure contrast ratios.
To do this, point the dome of your light meter directly at the main light source. Because the dome is three-dimensional, it will read light coming from other sources as well, which is fine because this is how your actors or subjects will be lit in real life.
Why Measure Contrast Levels?
Contrast levels refer to the difference between the brightest and darkest parts of your scene. It’s important to understand this because contrast affects the mood, tone, and clarity of your shot. For example, a high contrast scene (where the difference between light and dark areas is large) will create a dramatic or intense feeling. Low contrast scenes, on the other hand, have a softer, more relaxed look.
Watch this video for a great primer to the power of contrast ratios:
When you measure the light hitting different parts of the scene, you can control the contrast more effectively. This helps ensure your shots look consistent when cut together.
To get the best contrast readings, you need to know how your camera handles exposure. You’ll also want to light your scene to a specific aperture.
Once you’ve set this, you can fine-tune other settings like ISO, ND filters and LUTs to help you perfect the look you’re going for.
3. Using a Light Meter for Tighter Contrast Levels or Flat Surfaces
Sometimes, you don’t want light from other sources interfering with your reading. In these cases, you can retract the dome on your light meter if your model has this option.
The Sekonic LiteMaster Pro L-478D-U (Amazon, B&H) is one light meter I highly recommend.
This allows you to isolate the light coming from a specific source or area without contamination from other lights.
When Should You Retract the Dome?
Retracting the dome is useful when you’re measuring flat surfaces like walls or chroma key backgrounds.
Unlike actors or three-dimensional objects, flat surfaces don’t reflect light the same way, so you need to measure them differently. By isolating the light, you’ll get a more accurate reading of how much light is falling on the surface.
Know what you are measuring
When using a light meter, you’re usually measuring one of two things:
- F-stop or T-stop: These measurements tell you how much light is hitting the subject and help you calculate the contrast levels in your scene. For example, if one part of your scene reads T2.8 and another part reads T4, you know that there’s a one-stop difference. Using EV (Exposure Value) is also helpful because it makes these calculations easier. A good light meter will give you all these options.
- Lux or Foot candles: Lux is a measurement of light intensity. This is useful when you want to know how much light is hitting your subject so you can adjust your fixtures accordingly. Once you’re experienced, you’ll be able to judge light intensity by eye, but using a meter can help you get more precise measurements, especially in tricky lighting situations.
Advantages of Using an Incident Light Meter
There are several reasons why an incident light meter is a valuable tool for cinematographers. Here are the key advantages:
- Cameras don’t matter! An incident light meter gives you a direct reading of the light, regardless of your camera’s settings or features. You can adjust your camera to match your lighting style without worrying about its built-in meter.
- Lenses don’t affect readings. You can switch between lenses without worrying about how it affects the light meter’s reading. As long as you keep the same T-stop, your light meter will give you accurate results.
- Surface reflectance doesn’t matter. The reflectance of different surfaces like skin tones or fabrics won’t affect your light meter readings. This allows you to light your scene more consistently, without needing to constantly adjust for different textures or colors.
- Camera movement doesn’t matter. You can light the entire area without worrying about camera movement or angles. This gives you more flexibility when working with directors who may change their mind about camera placement.
Practice makes perfect!
To get the most out of your light meter, practice is key. Even the best cinematographers didn’t become experts overnight.
With regular use, you’ll develop a feel for how light interacts with your scene, and eventually, you may not need a meter at all! Many experienced cinematographers stop using light meters altogether because they’ve trained their eyes to see light in ways others can’t.
However, don’t be tempted to skip the light meter in your early days. It’s an essential tool that will help you understand light better.
Over time, as you gain experience, you’ll be able to predict how different lighting setups will look without needing constant meter readings. But until then, your light meter is a valuable resource for ensuring your scenes are lit consistently and professionally.
Together with a calibrated production monitor, you can do wonders with a light meter. If you’re looking for a good light meter, check out this comparison and my recommendations:
I hope you’ve found this useful! Let me know how you use light meters in the comments below.
