A sleek, modern graphical thumbnail for a 'Lighting distance calculator' web widget. It illustrates a stylized softbox light source with bright yellow light rays projecting onto a subject at varying distances along a 10-meter virtual stage.

Inverse Square Law Lighting Calculator

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Inverse Square Law Lighting Simulator

Calculate illuminance drop-off and required placement for camera setups

📷
Pos 1: 2.0m
🎬
Pos 2: 4.0m
0m (Key Light) 2.5m 5.0m 7.5m 10.0m
Initial Distance (d₁) 2.0 m
Initial Light Level (E₁) 1000 Lux
New Distance (d₂) 4.0 m
Target Light Level
250 Lux
At 4.0 m distance
Brightness Shift
-75%
Intensity change
Exposure Shift
-2.00 EV
F-stop compensation

Key Features

  • Dual Calculation Modes: Toggle between calculating expected light intensity (Lux) at a new distance or calculating the required light distance to achieve a target Lux value.
  • Interactive Visual Stage: Live graphical preview showing the relative positions of the light fixture, initial camera/subject position, and target position along a 10-meter virtual stage.
  • Exposure Metrics: Automatically outputs brightness change percentages and EV (Exposure Value/F-stop) differences for camera setting adjustments.

How to Use

  1. Select Mode: Use the top toggle buttons to choose whether you want to calculate Target Lux or Required Distance.
  2. Set Initial Values: Enter your starting setup—distance ($d_1$) and current illuminance ($E_1$ in Lux).
  3. Adjust Target Variable:
    • In Calculate Target Lux mode, adjust the New Distance ($d_2$) slider or input box to see the light drop-off.
    • In Calculate Required Distance mode, enter your desired Target Lux ($E_2$) to get the exact distance required.
  4. Read Results: Check the highlighted summary card for the primary answer, and review the EV Shift card to adjust camera aperture/ISO accordingly.

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