About This Site

The Lighting Ratio Calculator is a free tool designed to assist with "lighting design" in cinematography and photography.
It's engineered to help even beginners understand how to apply light and choose lighting equipment through "numerical comprehension."

When to Use It?

• When you want to create a lighting plan before a shoot.
• When you need to control the brightness (illuminance) of your subject.
• When you want to numerically check the balance between key light and fill light.
• When you're unsure which lighting equipment to use or from what distance.

Main Features

• Illuminance calculation based on Lux.
• Simulation of Lighting Ratios.
• Confirmation of exposure balance linked with ISO, F-stop, and shutter speed.
• Reverse calculation of light intensity reaching the subject from lighting distance and lumen output.

Guide to Understanding the Displayed Values

Automatically calculates the required Lux value at 1 meter based on your selected camera settings (ISO, F-stop, shutter speed).
By comparing this with the specifications provided by LED lighting manufacturers, you can simulate appropriate lighting equipment.

Enter the distance between the light and the subject to display the actual Lux/fc (foot-candles) reaching the subject's surface.
Use this as a guideline for adjusting light intensity, such as making it "a bit softer" or "1 stop brighter."

In the Lighting Ratio Calculator, the "Subject Illuminance (Lux/fc)" for each light source (Key/Fill/Back) and the Lighting Ratio (their difference) are updated in real-time. Here’s how to interpret them:

• Key Light: The main light illuminating the subject. The Lux/fc shown here is the baseline exposure level for the entire scene.
• Fill Light: Auxiliary light that lifts the shadow side. By checking its percentage or stop difference relative to the Key Light, you can numerically grasp the contrast intensity.
• Backlight (Rim/Hair Light): Light from behind the subject that accentuates its outline. Use this value as an indicator for adjusting separation from the background and three-dimensionality, or as a measure for illuminating the background itself.

For example, a Key to Fill ratio of 2:1 (1 stop difference) creates a natural, soft look, while 8:1 (3 stops difference) results in a dramatic, high-contrast image. Adjust the values to design the tone according to your purpose.

Benefits of Use

1. Understand Lighting Numerically

   Grasp the often challenging "brightness balance" with concrete numbers.

2. Design Lighting Before the Shoot

   Decide on lighting equipment and placement before arriving on set, reducing setup time.

3. Recreate the Same Lighting

   Save your settings to instantly reproduce the same lighting on a different day. Effective for films and commercials where shot-to-shot consistency is crucial.

Recommended For

• Videographers and photographers trying lighting for the first time.
• Video creators in small teams aiming for efficient shoots.
• Instructors teaching lighting basics at film schools or workshops.
• Individuals who want to understand exposure theoretically, even without a light meter.

Light is the most crucial element in determining the “impression” of videos and photos.
With the Lighting Ratio Calculator, anyone can achieve lighting design based on calculation and intent, rather than relying on a vague feeling.
Regardless of your shooting experience, please feel free to use it in your daily creative work.

Ryo Takahashi JSC

Cine Frame