Exposure Value (EV) vs. Cinema Shutter Angle & 180° Rule
Comparing 2 standards across 11 specifications. 11 key differences identified.
Exposure Value (EV, standardized under ISO 2720) is a logarithmic base-2 scale quantifying combinations of shutter speed and relative aperture that yield identical photographic exposures (EV = log_2(N² / t) at ISO 100). Governs light metering, auto-exposure compensation, dynamic range benchmarks, and the classic 'Sunny 16' outdoor rule.
Shutter Angle (measured in degrees from 0° to 360°, originating from circular rotary disc shutters in 35mm motion picture cameras) is the cinematic standard for measuring exposure time relative to frame rate (Shutter Speed = Frame Rate × 360° / Shutter Angle). The universal '180-Degree Shutter Rule' (exposure time = 1 / (2 × Frame Rate)) delivers natural, organic motion blur that mimics human eye persistence.
Specification Comparison Table
11 Parameters| Parameter / Spec | ||
|---|---|---|
|
Mathematical Formula
|
EV = log₂(N² / t) — where N is f-number and t is shutter speed in seconds (at ISO 100) | Shutter Speed (t) = 1 / (Frame Rate × (360° / Shutter Angle)) |
|
EV 0 Baseline
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Aperture f/1.0 with a 1.0-second shutter speed at ISO 100 | — |
|
Sunny 16 Rule (EV 15)
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Bright direct outdoor sunlight = EV 15 (Set aperture to f/16, shutter speed = 1 / ISO speed, e.g. 1/100s at ISO 100) | — |
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Typical Real-World EV Benchmarks
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EV -4: Full moon night sky | EV 4: Candlelight interior | EV 7: Typical home interior | EV 12: Overcast day | EV 15: Sunny beach/snow | — |
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Auto-Focus Low-Light Rating
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Modern mirrorless AF sensitivity is rated down to EV -6 to EV -9 (operational in near pitch-black darkness) | — |
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Dynamic Range Measurement
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Expressed in EV stops (e.g. 14 EV of sensor dynamic range = a 16,384:1 contrast ratio) | — |
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180° Standard Shutter Rule
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— | Exposure time is exactly half of the frame duration: at 24 fps = 1/48 sec | at 30 fps = 1/60 sec | at 60 fps = 1/120 sec | at 120 fps = 1/240 sec |
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90° Narrow Shutter (Action Effect)
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— | Fast exposure (1/96 sec at 24 fps) — crisp, staccato, jittery combat motion (Saving Private Ryan effect) |
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360° Open Shutter (Dream / Smear)
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— | Full-duration exposure (1/24 sec at 24 fps) — extreme motion blur, dreamy light trails, maximum low-light intake |
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172.8° Shutter Angle (Flicker Reduction)
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— | Eliminates 50 Hz European AC electrical lighting flicker when shooting at 24 fps in PAL regions |
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Cinema Camera Standard
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— | ARRI Alexa, RED, Sony FX6/FX9, Canon C300, and Blackmagic display shutter in degrees to maintain constant motion blur during frame rate ramps |