Arri Frame Rate Calculator

ARRI Frame Rate Settings

Calculate optimal frame rates for your ARRI camera based on motion blur requirements and recording duration.

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ARRI Camera Frame Rate Capabilities

Camera Model	Max FPS (ARRIRAW)	Max FPS (ProRes 4444 XQ)	Max Resolution	Typical Data Rate (ARRIRAW)
ARRI ALEXA 65	60 fps	N/A	6560 x 3100	~5700 MB/s
ARRI ALEXA Mini LF	90 fps (Open Gate)	150 fps (Open Gate 4.5K)	4.5K / Open Gate	~3000 MB/s
ARRI ALEXA SXT	120 fps (2K)	120 fps (2K)	2880 x 2160 (Open Gate)	~2200 MB/s
ARRI ALEXA Mini	200 fps (2K)	200 fps (2K)	2880 x 1620 (Open Gate)	~2000 MB/s
ARRI ALEXA XT	120 fps (2K)	120 fps (2K)	2880 x 2160 (Open Gate)	~2200 MB/s

What is ARRI Frame Rate?

ARRI frame rate refers to the number of individual still frames a motion picture camera, specifically an ARRI camera, captures or records per second. This fundamental setting dictates how motion is represented on screen. A higher frame rate captures more moments per second, leading to smoother motion representation, while a lower frame rate captures fewer moments, which can be used for stylistic slow-motion effects when played back at a standard rate, or may result in choppier motion if not handled correctly. For filmmakers using high-end ARRI cameras, understanding and precisely controlling frame rate is crucial for achieving the desired aesthetic, managing data flow, and optimizing storage. This ARRI frame rate calculator helps you navigate these technical parameters.

This calculator is particularly useful for cinematographers, camera assistants, DITs, and post-production professionals working with ARRI digital cinema cameras. Common misunderstandings often revolve around the difference between the project frame rate (e.g., 24 fps for cinema) and the camera's maximum recording frame rate, as well as how shutter angle directly affects motion blur and exposure.

ARRI Frame Rate Formula and Explanation

The core of understanding frame rate settings on an ARRI camera involves a few key calculations. The primary relationship is between shutter angle, project frame rate, and the resulting motion blur and exposure time.

Effective Shutter Speed Calculation

The shutter angle directly controls the duration each frame is exposed to light. A larger shutter angle means the sensor is exposed for a longer period during each frame's capture cycle, resulting in more motion blur and brighter exposure. A smaller shutter angle reduces exposure time and motion blur.

Formula:

Effective Shutter Speed (sec) = (Shutter Angle / 360°) * (1 / Project Frame Rate (fps))

Maximum Possible FPS

This is determined by the camera's internal processing capabilities, sensor readout speed, and chosen recording codec (e.g., ARRIRAW, ProRes). Different ARRI camera models and configurations have different maximum FPS limits at various resolutions and codecs.

Data Rate and Storage Calculation

These are estimated based on the selected project frame rate, resolution, codec, and the camera's internal processing limits for the chosen sensor size.

Formula:

Required Data Rate (MB/s) ≈ (Project Frame Rate * Resolution Area * Bit Depth * Color Sampling) / 8 / 1000 (This is a simplified estimation; actual rates vary greatly by codec and compression)

Storage Needed (GB) = (Required Data Rate (MB/s) * Recording Duration (min) * 60 sec/min) / 1000 MB/GB

Variables Table

Variable Definitions for Frame Rate Calculation

Variable	Meaning	Unit	Typical Range
Shutter Angle	The portion of the camera's rotation cycle that the shutter is open.	Degrees (°)	0° – 360° (commonly 45°, 90°, 180°, 270°, 360°)
Project Frame Rate	The intended playback speed of the final footage.	Frames per second (fps)	23.976, 24, 25, 30, 48, 60, 120, etc.
Effective Shutter Speed	The actual time each frame is exposed to light.	Seconds (sec)	Varies widely based on shutter angle and frame rate.
Maximum Possible FPS	The highest frame rate the camera can record at a given resolution/codec.	Frames per second (fps)	Depends on camera model (e.g., 30 fps to 1000+ fps).
Recording Duration	The continuous length of time footage needs to be captured.	Minutes (min)	1 – 120+
Sensor Size / Camera Model	Specific ARRI camera model or sensor format.	Unitless (Categorical)	ALEXA Mini, ALEXA LF, ALEXA 65, etc.
Required Data Rate	The speed at which data must be written to media.	Megabytes per second (MB/s)	Hundreds to thousands MB/s.
Storage Needed	Total storage space required for the duration.	Gigabytes (GB)	Depends on duration, frame rate, and codec.

Practical Examples

Let's explore how this ARRI frame rate calculator can be used in real-world scenarios:

Example 1: Standard Cinematic Shoot

• Scenario: Shooting a narrative film scene requiring a cinematic look with natural motion blur.
• Inputs:
  • Shutter Angle: 180°
  • Project Frame Rate: 24 fps
  • Sensor Size: ARRI ALEXA Mini (for context on limits)
  • Desired Recording Duration: 15 minutes
• Calculator Output:
  • Effective Shutter Speed: 1/48 sec
  • Max Possible FPS: (e.g., 200 fps for ALEXA Mini at 2K)
  • Required Data Rate: (e.g., ~2000 MB/s for ARRIRAW)
  • Storage Needed: ~1800 GB (1.8 TB)
• Analysis: A 180° shutter at 24 fps provides the classic motion blur. The high data rate and storage requirement highlight the need for robust media and storage solutions when shooting ARRIRAW for extended periods. If ProRes were chosen, data rates and storage would be significantly lower.

Example 2: High-Speed Action with Reduced Motion Blur

• Scenario: Capturing fast-moving sports action where a sharper image with less blur is desired, potentially for slow-motion playback.
• Inputs:
  • Shutter Angle: 90°
  • Project Frame Rate: 60 fps (for smoother action playback)
  • Sensor Size: ARRI ALEXA LF (known for high frame rate capabilities)
  • Desired Recording Duration: 5 minutes
• Calculator Output:
  • Effective Shutter Speed: 1/240 sec
  • Max Possible FPS: (e.g., 90 fps for ALEXA Mini LF Open Gate ARRIRAW)
  • Required Data Rate: (e.g., ~3000 MB/s for ARRIRAW)
  • Storage Needed: ~900 GB
• Analysis: The 90° shutter significantly reduces motion blur, making fast action clearer. Shooting at 60 fps provides smoother playback for action sequences. The calculator confirms the camera's capability to handle these settings and estimates the substantial data and storage demands. If shooting at the camera's maximum 90 fps was desired for extreme slow motion, the data rate and storage requirements would increase dramatically.

How to Use This ARRI Frame Rate Calculator

1. Input Shutter Angle: Enter the desired shutter angle in degrees. 180° is standard for filmic motion blur. Smaller angles reduce blur (sharper image, less light), while larger angles increase blur (more motion blur, more light).
2. Set Project Frame Rate: Input your final intended frame rate (e.g., 24 fps for cinema, 30 fps for broadcast, 60 fps for smoother motion or slow-motion potential).
3. Select Camera Sensor Size: Choose the ARRI camera model or specific sensor format you are using. This is crucial as different models have vastly different maximum frame rates and recording limits.
4. Enter Recording Duration: Specify how long you need to record in minutes for storage and data rate calculations.
5. Click 'Calculate Settings': The calculator will instantly provide:
   • Effective Shutter Speed: The actual exposure time per frame.
   • Max Possible FPS: The highest rate your selected camera can achieve (useful for understanding limitations or potential for slow-motion).
   • Required Data Rate: The speed required for continuous recording.
   • Storage Needed: The estimated total storage for your desired duration.
6. Interpret Results: Use the output to ensure you have appropriate media, sufficient storage, and that your chosen settings align with your creative and technical requirements.
7. Use the Chart and Table: Refer to the visual chart and table for broader context on frame rate capabilities across different ARRI models.

Key Factors That Affect ARRI Frame Rate Decisions

1. Creative Intent (Motion Blur): The primary artistic decision. Do you want the classic cinematic motion blur (typically 180° shutter), or a sharper, more "staccato" look with less blur (achieved with smaller shutter angles or higher frame rates)?
2. Lighting Conditions: Lower shutter angles or higher frame rates require more light because the exposure time per frame is shorter. You may need to increase ISO, use wider apertures, or add more lighting. ARRI cameras are known for their excellent low-light performance, but physics still apply.
3. Camera Model and Sensor: Different ARRI cameras (e.g., ALEXA Mini LF vs. ALEXA 65) have distinct maximum frame rates, resolutions, and recording formats (ARRIRAW vs. ProRes), significantly impacting what's possible.
4. Codec and Recording Format: ARRIRAW offers maximum flexibility in post-production but demands significantly higher data rates and storage than Apple ProRes formats (like ProRes 4444 XQ). Choosing the right codec is a balance of quality, workflow, and resource management.
5. Project Requirements: Standards like 23.976/24 fps for film, 25 fps for PAL broadcast, or 29.97 fps for NTSC broadcast dictate your base project frame rate. High frame rates (60 fps, 120 fps) are often used for smoother action or deliberate slow-motion effects.
6. Playback System Limitations: Ensure your editing system and final delivery format can handle the chosen frame rate and resolution without performance issues.
7. Storage and Media Speed: High frame rates and uncompressed/lossless formats generate massive amounts of data. You need fast, reliable media cards and sufficient onboard storage or tethered recording solutions.
8. Post-Production Workflow: Consider the demands on your editing suite, color grading software, and final rendering time. Higher frame rates and raw footage require more powerful hardware and longer processing times.

FAQ

Q: What is the difference between Project Frame Rate and Camera Frame Rate?

A: The Project Frame Rate (or Timeline Frame Rate) is the final speed your edited video will play at (e.g., 24 fps for film). The Camera Frame Rate is what the camera actually records. You can often record at a higher frame rate than your project rate for slow-motion effects (e.g., recording at 60 fps and playing it back at 24 fps).

Q: How does shutter angle affect exposure on an ARRI camera?

A: A larger shutter angle (e.g., 360°) lets light hit the sensor for the entire duration of the frame's capture cycle, resulting in maximum exposure and maximum motion blur. A smaller shutter angle (e.g., 45°) reduces the time the sensor is exposed, leading to less light (underexposure) and less motion blur.

Q: Can I shoot ARRIRAW at very high frame rates on all ARRI cameras?

A: No. High frame rate capabilities, especially in ARRIRAW, are limited by the specific camera model's processing power, sensor readout speed, and media interface. For example, the ALEXA Mini LF supports higher frame rates in ARRIRAW than older ALEXA models. Always check the camera's technical specifications.

Q: What's the optimal frame rate for fast action?

A: For smoother representation of fast action without excessive blur, a higher project frame rate (like 60 fps or higher) is often preferred. Combined with a faster effective shutter speed (smaller shutter angle), this keeps motion sharp. You can then slow this footage down in post if desired.

Q: How much storage does 1 minute of ARRI footage take?

A: This varies enormously. A minute of 4K ProRes 4444 XQ might be around 60-100 GB, while a minute of ALEXA 65 ARRIRAW at its highest settings could be over 3000 GB (3 TB). The calculator provides estimates based on your inputs.

Q: What does 'Open Gate' mean on ARRI cameras?

A: 'Open Gate' refers to recording using the camera's entire sensor area, providing the maximum possible resolution and field of view. This often allows for higher frame rates or more reframing flexibility in post-production compared to using specific sensor modes (like 16:9 or 4:3).

Q: Is 180-degree shutter the only option?

A: No. While 180° is standard for achieving natural motion blur that matches the look of traditional film at 24 fps, you can use other shutter angles. A 90° shutter provides half the motion blur and requires double the light. A 360° shutter provides maximum motion blur and light.

Q: How does the calculator estimate data rate and storage?

A: The calculator uses simplified formulas based on common data rates for selected camera models and formats. Actual data rates can fluctuate based on scene complexity, compression algorithms, and specific media card performance. The values provided are reliable estimates for planning purposes.

Related Tools and ARRI Resources

Explore these related tools and resources for more insights into cinematography and ARRI camera systems:

• Aspect Ratio Calculator: Understand different cinematic aspect ratios.
• Exposure Value (EV) Calculator: Calculate exposure settings based on light.
• Depth of Field Calculator: Determine your zone of focus.
• Lens to Sensor Distance Calculator: Essential for certain rigging setups.
• ARRI Camera Comparison Guide: Detailed breakdown of different ARRI models.
• Understanding Video Codecs: Learn the differences between RAW and ProRes.
• Guide to Cinematic Motion Blur: In-depth look at shutter speed and its impact.