Frame Rate Shutter Speed Calculator

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Frame Rate to Shutter Speed Calculator

Common values: 23.976, 24, 25, 30, 50, 60, 120
180° is the cinematic standard for natural motion blur.
Ideal Shutter Speed
Decimal Exposure Time
Nearest Camera Settings (1/3 stops)

*Note: Most DSLR and Mirrorless cameras do not have infinite shutter precision. Use the "Nearest Camera Setting" that is closest to the Ideal Shutter Speed.

Understanding the 180-Degree Shutter Rule

In cinematography and videography, the relationship between your frame rate and shutter speed dictates how motion is perceived by the viewer. This calculator helps you convert Shutter Angle (a terminology from film cameras) into Shutter Speed (measured in fractions of a second, common in digital cameras).

What is the 180-Degree Rule?

The 180-degree rule is a standard industry guideline that states your shutter speed should be approximately double your frame rate to achieve natural-looking motion blur.

Mathematically, the formula is:

  • Shutter Speed = 1 / (2 × Frame Rate)

For example, if you are shooting at 24 fps, your shutter speed should be 1/48th of a second. Since most DSLRs don't have a 1/48 setting, you would round to the nearest available setting, usually 1/50.

Shutter Angle vs. Shutter Speed

Cinema cameras often use "Shutter Angle" to describe exposure time. This comes from the rotary disc shutter in mechanical film cameras. The size of the opening in the spinning disc determines the exposure.

  • 180° Angle: Normal motion blur (Standard).
  • 90° Angle (Skinny Shutter): Less motion blur, crisp action (Saving Private Ryan effect).
  • 360° Angle (Open Shutter): More motion blur, dreamlike or smeared look.

Common Frame Rate & Shutter Speed Combinations

Use this quick reference guide for the most common settings using the 180-degree rule:

  • 24 FPS: Ideal 1/48 sec (Use 1/50 sec on most cameras)
  • 30 FPS: Ideal 1/60 sec
  • 60 FPS: Ideal 1/120 sec (Use 1/125 sec)
  • 120 FPS: Ideal 1/240 sec (Use 1/250 sec)

Why Calculation Matters

Setting the incorrect shutter speed can result in footage that looks "stuttery" (shutter speed too fast) or "soapy" (shutter speed too slow). By calculating the precise mathematical requirement, you can ensure your manual camera settings are optimized for the cinematic look you intend to create.

function calculateShutterDetails() { // 1. Get input values var fpsInput = document.getElementById('frssc_fps').value; var angleInput = document.getElementById('frssc_angle').value; // 2. Parse values var fps = parseFloat(fpsInput); var angle = parseFloat(angleInput); // 3. Validation if (!fps || isNaN(fps) || fps <= 0) { alert("Please enter a valid Frame Rate (FPS)."); return; } if (!angle || isNaN(angle) || angle <= 0) { alert("Please enter a valid Shutter Angle (degrees)."); return; } // 4. Calculate Logic // Formula: Shutter Speed Denominator = (360 * FPS) / Angle // Because Exposure Time = Angle / (360 * FPS) var denominator = (360 * fps) / angle; var exposureTime = 1 / denominator; // 5. Determine Nearest Standard Camera Setting // Common 1/3 stop shutter speeds var standardSpeeds = [ 24, 25, 30, 40, 48, 50, 60, 80, 100, 120, 125, 160, 200, 240, 250, 320, 400, 500, 640, 800, 1000, 1250, 1600, 2000, 4000, 8000 ]; var closest = standardSpeeds[0]; var minDiff = Math.abs(denominator – closest); for (var i = 1; i < standardSpeeds.length; i++) { var diff = Math.abs(denominator – standardSpeeds[i]); if (diff < minDiff) { minDiff = diff; closest = standardSpeeds[i]; } } // 6. Format Results // Round denominator to 2 decimal places if it's not an integer, for display cleanly var displayDenominator = (denominator % 1 === 0) ? denominator : denominator.toFixed(2); var resultFraction = "1/" + displayDenominator + " sec"; var resultDecimal = exposureTime.toFixed(5) + " sec"; var resultNearest = "1/" + closest + " sec"; // 7. Update DOM document.getElementById('frssc_ideal_fraction').innerText = resultFraction; document.getElementById('frssc_decimal_time').innerText = resultDecimal; document.getElementById('frssc_nearest_setting').innerText = resultNearest; // Show results container document.getElementById('frssc_results').style.display = 'block'; }

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