The Film Exposure Foot-Candle & Cine Light Estimator evaluates three-variable illumination ratios, geometric mean factors, and photometric efficiency ratings.

### Operational Formulas & Mathematical Ratio The calculator processes three user-specified lighting parameters: - **Calculated Photometric Result**: $$\text{Result} = \frac{\text{Primary Illumination} \times \text{Operating Factor}}{\max(0.01, \text{Safety Factor})}$$ - **Root Factor (Geometric Mean)**: $$\text{Root Factor} = \sqrt{\max(0, \text{Primary Illumination} \times \text{Operating Factor})}$$ - **Photometric Efficiency Rating**: $$\text{Efficiency (\%)} = \min\left(100, \max\left(0, \frac{\text{Primary Illumination}}{\text{Primary Illumination} + \text{Operating Factor}} \times 100\right)\right)$$

### Worked Calculation Example Evaluating baseline scene lighting values: - **Primary Dimension / Load (Illumination Input)**: 100 - **Operating Coefficient (Sensitivity Factor)**: 20 - **Safety / Rate Factor (Aperture Scale)**: 5 - **Calculated Result**: $(100 \times 20) / 5 = 2000 / 5 = 400.00$ - **Root Factor**: $\sqrt{100 \times 20} = \sqrt{2000} \approx 44.72$ - **Efficiency Rating**: $[100 / (100 + 20)] \times 100 = (100 / 120) \times 100 \approx 83.3\%$

### Scope & Cinematography Exposure Note This utility implements an algebraic ratio estimator. For certified set exposure, cinematographers use standard incident exposure equations combining foot-candles ($FC$), shutter angle/speed ($t$), lens transmission ($T$), and sensor sensitivity ($ISO$): $$\text{Foot-Candles} = \frac{25 \times T^2}{t \times \text{ISO}}$$ calibrated against calibrated light meters.

### In-Browser Processing & Privacy Calculations update dynamically in your web browser. No set lighting plans, camera exposure logs, or production notes are uploaded to any server.