nreal Engine Workshop – Session 13 Summary
📌 Topic: Exposure Settings – Aperture, Shutter Speed, ISO, and White Balance
🔺 Exposure Triangle Fundamentals
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Exposure = Controlled light hitting the camera sensor/film.
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Aim: Maintain consistent light intensity (e.g., 100 watt-equivalent) regardless of lighting conditions.
🔘 1. Aperture (F-stop)
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Controls light entry by adjusting lens opening diameter.
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Lower f-stop (e.g., f/2) = More light; Higher f-stop (e.g., f/16) = Less light.
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Each full stop halves or doubles the light.
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Example: f/2 (8000W) → f/2.8 (4000W) → f/4 (2000W), etc.
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Aperture also affects Depth of Field.
⏱️ 2. Shutter Speed
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Determines how long the sensor/film is exposed to light.
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Shorter exposure = less light; longer = more light.
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Still photos: slower shutter speed can compensate for low light (e.g., 1/4 sec).
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Video cameras (e.g., 30fps): limited to fixed frame rate.
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Cannot reduce FPS below standard without impacting playback smoothness.
📈 3. ISO (Film/Sensor Sensitivity)
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Amplifies signal from the sensor to simulate more light.
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Higher ISO = brighter image in low light (e.g., ISO 800 needs less light than ISO 100).
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Trade-off: higher ISO introduces noise or grain (especially in mid-tones).
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Modern cameras (e.g., iPhone 16 Pro) use AI-based noise reduction for low-light clarity.
🎨 White Balance & Color Temperature
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Ensures white appears white under different light sources.
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Artificial light (e.g., tungsten) alters perceived color.
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Controlled using Color Temperature:
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Red @ 1600K, Yellow @ 3200K, White @ 5000K, Blue @ 6000K+
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White Balance compensates by digitally adjusting color channels.
🌀 Mechanical vs Electronic vs Global Shutter
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Mechanical/Rolling Shutter: Opens/closes physically; used in old DSLRs/cinema.
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Electronic Shutter: Uses current; seen in mobile/digital cameras.
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Global Shutter: Captures entire sensor at once → no distortion with fast motion.
🐢 Motion Blur & Frame Rate
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Human eye ≈ 32 fps sensitivity; fast motion causes blur.
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High-speed photography (e.g., 480–980 fps) enables smooth slow-motion playback.
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Unreal Engine supports high FPS for fluidity in gameplay and animation.
⚙️ Practical Use in Unreal Engine
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All these settings (Aperture, ISO, Shutter Speed) can be simulated with Cine Cameras.
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Helps achieve cinematic lighting and depth in virtual shots.
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White balance and exposure settings are key for realistic visual effects.
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