How to recreate lighting in post?
In cinematography, lighting always plays a vital role in creating a visual mood. In general, lighting can enhance images, create depth, and support the mood and atmosphere of your story. Lighting is so important during the shooting stage, which involves the efforts of different roles, from the director to the DP, to the gaffer. However, in order to achieve the perfect look and smooth flaws from the footage, lighting can also be adjusted during the post-production stage. In this article, we will walk you through the key elements of lighting, what can cinematographers do on set, and how colorists can recreate lighting in the post to achieve better storytelling.
Key Elements of Recreating lighting in Post
lighting Quality
Lighting quality describes the softness of the shadows and how they behave. As light travels in waves, softness determines how they disperse, so you are able to tell how soft or hard light is based on the shadows it creates. Therefore, lighting quality usually boils down to two categories: hard light and soft light.
For hard lighting, it’s very directional, casts shadows with sharp edges, and provides a high-contrast look. Cinematographers tend to use hard lighting to add dimension and create a strong sense of drama to achieve an edgy look. In contrast, soft lighting looks more natural, with balanced brightness and soft shadows. It brings a smoother look when it comes to the transition between the light and the shadows.
In order to achieve the desired look, it’s highly recommended that cinematographers should light the scene in ideal contrast if possible because colorists have some limitations in dealing with the complexity in different lighting quality and adjusting any harshness and flaws in the footage if the contrast is too large.
Intensity/Brightness
Intensity refers to the brightness of the light. The intensity of the key light can drive exposure decisions, which are key to achieving a certain look for your story. In short, good control of the image brightness can maximize the retention of all details, enhance the images and support the atmosphere of the story. Conversely, overexposure and underexposure can also result in incomplete details and noise. Therefore, it’s easier for colorists to adjust those scenes with balanced brightness.
Color Temperature
The color temperature is usually used to describe the warmth or coolness of a light source. Filmmakers use different color temperatures to help give nuance to their visual storytelling and bring different feelings/ emotions to the audiences. The color temperature is measured using the Kelvin scale, in which light will progress from yellow color to white color, to blue color. Two of the most commonly used in the film are daylight (5600K) and tungsten (3200K).
It is possible for colorists to correct the color of the image with different white balance (color temperature) settings. However, if you want to achieve a natural daylight look, it’s better to match the lighting to the camera’s native color temperature (usually 5600K), rather than adjusting directly from tungsten lighting. Also, changes in hue are relatively easy to adjust as long as skin tone is not involved.
Direction of the Light
Lighting not only has the characteristics of being harder or softer, brighter or darker, warmer or cooler, but it also has a directional quality that you can use to enhance your subject and the images. The three most common directions that are being used in cinematography are key light, fill lighting and back light. Different directions of the light can provide different illumination and atmosphere.
We need to pay attention to the continuity of the light source, especially when we are shooting different angles of the same scene. As one of the common light sources, the sun is harder to keep track of, and due to the limitation of the shooting time, you might end up having inconsistent shots. In this circumstance, it’s more important to keep the same lighting ratio of the character’s face.
Common Situations of Recreating Lighting
Day for Night
Day for night is a set of cinematic techniques used to simulate a night scene while shooting in daylight. It can be applied to both interior and exterior shoots. Before moving to the post-production stage, the lighting in the shooting stage is important in terms of laying a good foundation for the color grading in the later stage. Here are some suggestions when you are shooting day for night.
Shooting Interior
For shooting day for night interior, you should pay close attention to how the windows. Usually, you need to block it completely or dim them down.
Shooting Exterior
Shooting exterior scenes day for night is much more complicated and has more factors to be considered. As sunlight and moonlight are similar in light quality but dramatically different in intensity, it's important to preserve some of the necessary contrasts to avoid being too flat and unreal. Moreover, you should avoid sky in every single shot to make sure the effectiveness of the scenes, unless you plan to add a VFX step into your pipeline.
Generally, colorists will crush the image a lot to achieve a certain look in the post. Therefore, it’s better to have the characters’ figures brighter than the background so they won’t blend together. Also, if you want to show more details of the subjects, it’s important to light it up a little bit, otherwise, it will be hard to bring it up from the shadows.
Make the Subject Pop
In order to achieve a better look of the image, colorists have the ability to use windows to enhance key light or fill light, which can also help to adjust the contrast on the face. When kick light is too bright on the hair, colorists might reduce the highlights there to create a more balanced image.
Creating the atmosphere
In lighting, colorists can create a sense of atmosphere by controlling three things: practical, windows, and flares. In the early stage, the brightness of the practical and window should be adjusted to avoid being distracting and overexposed. However, if there are no details in the highlights, colorists won’t be able to dim them down in post.
Flares can be added in both early and later stages while adding flares in the early stage can be more authentic. As flares may change the contrast and color of the image dramatically, you should pay more attention to this because there are some moments you want to see the character clearly.
Creating Keyframes
Colorists often use keyframes when there is an exposure or color temperature change in the same shot. This often happens when filming documentaries using auto exposure or auto white balance. By creating keyframes and adjusting every moment, colorists are able to smooth out the change. Another use of the keyframe is creating turn-off/dim-down lights or flash effects, which are very common in horror movies.
For the worst-case scenario when there are too many flaws in the shooting stage, colorists will try their best to match the contrast of the image and make it black and white, or a sepia look. In order to avoid this, it is highly recommended to do a camera/ lens test and learn how the camera/lens renders the image.
How to achieve the best results?
For early stage preparation
Use a light meter (incident reading for skin tone and reflective reading for background/foreground) to keep the lighting consistent
Keep the light ratio and direction consistent
Use the right exposure. Don’t go too overexposed or underexposed
For post-production
Communicate with the cinematographer to discuss details and desired visual image
Correct flaws that couldn’t be fixed on set
Learn the director and DP’s intention, enhance what they to achieve, and reduce the distracting things in the image
