Anamorphic Squeeze Factor Explained: How to Calculate What You Are Actually Shooting
The Editor Who Received Squeezed Footage Without Being Told
A post supervisor receives a hard drive from a production. The editor opens the files in DaVinci Resolve. Every shot looks like everyone on screen is 30% taller and thinner than a real person. The DIT didn't include a note about the anamorphic squeeze factor. The editor doesn't know whether the camera recorded 1.33x or 2x squeeze, or what sensor format the camera was using. Without that information, she can't set up the correct desqueeze in Resolve and can't be certain the field of view she's looking at is what the DP intended. She emails the DIT. The DIT is on another production and doesn't respond for two days. The edit doesn't start.
Anamorphic squeeze is one of the most underspecified parts of a production's camera report, and the confusion it creates in post is entirely preventable. This post covers the math behind squeeze factor, how it changes what you're actually capturing, how to confirm it on set, and what to pass to the post team.
What Squeeze Factor Is and What It Does
Anamorphic lenses use a cylindrical optical element that compresses the image horizontally as it passes through the lens. The camera sensor then records this compressed (squeezed) image. The squeeze factor describes how much horizontal compression the lens applies:
- 1.33x squeeze: The horizontal dimension is compressed by a factor of 1.33. A 16:9 sensor frame becomes a 2.39:1 frame after desqueeze (16:9 x 1.33 = 2.39:1 approximately).
- 2x squeeze: The horizontal dimension is compressed by a factor of 2. A 4:3 sensor frame becomes approximately 2.67:1 after desqueeze. A 16:9 frame becomes 3.56:1 -- typically extracted as 2.39:1 with some vertical crop.
The formula for final aspect ratio:
Final Aspect Ratio = (Sensor Aspect Ratio) × Squeeze FactorFor example: BMPCC 6K in its native 3:2 recording mode with a 1.5x squeeze anamorphic lens:
3:2 × 1.5 = 4.5:2 = 2.25:1 final aspect ratio.
The Anamorphic Desqueeze Calculator handles this calculation for any combination of sensor aspect ratio and squeeze factor, including intermediate values like 1.5x and 1.8x.
The Capture vs. Display Distinction
What the sensor records: A squeezed image. The pixels are all there but the proportions are distorted horizontally. This is the "native" file that comes off the card.
What you see after desqueeze: The image with horizontal expansion applied, restoring correct proportions. This is what the DIT sets up on the monitor and what the colorist sets in Resolve.
What the lens sees (the actual field of view): The field of view is affected by squeeze in the horizontal dimension only. A 50mm anamorphic lens with 2x squeeze captures the horizontal field of view of a 25mm spherical lens but the vertical field of view of a 50mm spherical lens. The depth of field behavior follows the nominal focal length (50mm), but the horizontal coverage is doubled.
This is the most important and most misunderstood aspect of anamorphic shooting: the marked focal length is not the effective horizontal focal length. Use the Field of View Calculator with the squeeze factor input to find the actual horizontal field of view before ordering anamorphic glass.
Common Squeeze Factors and Their Results
| Squeeze Factor | Common Lens Examples | Typical Sensor | Final Aspect Ratio |
|---|---|---|---|
| 1.33x | Sirui 50mm T2.9, Laowa Nanomorph | S35, MFT | 2.39:1 (from 16:9) |
| 1.5x | Lomo Squarefront | S35 (from 2.39:1 recorded) | 2.39:1 (from 1.59:1) |
| 1.8x | Hawk 1.8x anamorphic | S35 | 2.39:1 (from 1.33:1 mode) |
| 2x | Cooke Anamorphic/i, ARRI Signature Anamorphic | Full Frame, LF | 2.39:1+ (from 1.20:1 extract) |
Note that multiple squeeze factors can all produce a 2.39:1 final image, but they achieve it from different sensor aspect ratios and at different field of view expansions. A 2x squeeze on a 4:3 Super 35 sensor produces 2.39:1 after slight vertical crop. A 1.33x squeeze on a 16:9 sensor produces 2.39:1 directly. The visual result at final aspect ratio is the same, but the capture workflow is different.
Three Production Scenarios
Scenario 1: BMPCC 4K with Sirui Anamorphic Lenses
The BMPCC 4K has a Micro Four Thirds sensor with a native 4:3 aspect ratio. The Sirui 50mm T2.9 anamorphic has a 1.33x squeeze designed for MFT. The calculation: 4:3 (1.33:1) × 1.33 squeeze = 1.77:1, which desqueezes to approximately 16:9. This is correct for the lens: the Sirui 1.33x series is specifically designed to produce a widescreen result from the MFT sensor.
However, if the same BMPCC 4K records in 16:9 crop mode instead of native 4:3, the calculation changes: 1.78:1 × 1.33 = 2.37:1. This is closer to 2.39:1. The DP needs to confirm which recording mode the camera is in and which squeeze factor the lens applies, and pass both figures to post. Use the Anamorphic Desqueeze Calculator to confirm the output ratio before the shoot.
Scenario 2: ARRI ALEXA Mini LF with 2x Anamorphic
The ALEXA Mini LF records in LF Open Gate mode at 4096 x 3072, which has a 1.33:1 aspect ratio. With a 2x anamorphic lens, the final aspect ratio after desqueeze is 1.33 × 2 = 2.66:1. The intended final delivery is 2.39:1. This means vertical crop is required in post. The DIT sets the monitor to show the desqueezed image with the 2.39:1 extraction zone marked. The DP frames within that zone. Anything above or below the zone is captured but not used in the 2.39:1 delivery. This gives compositional flexibility but requires discipline in framing -- subjects too high in the desqueezed frame may be cropped in the 2.39:1 extract.
Scenario 3: Vintage Lens, Unknown or Non-Standard Squeeze
A DP rents a vintage Soviet anamorphic scope lens from a private collection. The squeeze factor is listed as "approximately 2x" with no test data. Before the shoot, the DP films a test chart with a known dimension (a standard 600mm door) at a known distance (5 meters). The door appears in the squeezed image and the DP measures the pixel width of the door in the frame. Using the Anamorphic Desqueeze Calculator with the measured squeeze ratio from the test, the DP confirms the actual squeeze factor is 1.92x, not 2.0x. The post supervisor is notified to use 1.92x as the desqueeze value in Resolve rather than the assumed 2.0x.
Pro Tips
Tip 1: Always include the squeeze factor and sensor recording mode in the camera report on every shooting day. The minimum required information for post is: camera model, recording mode (sensor crop, aspect ratio), lens focal length, and squeeze factor. A camera report that says "BMPCC 4K, 50mm anamorphic" without the squeeze factor and recording mode is incomplete and will cause post confusion.
Tip 2: When monitoring anamorphic footage on set, always monitor with desqueeze applied at the correct squeeze factor. Framing in the squeezed image distorts depth perception and makes compositional decisions unreliable. Most DITs apply desqueeze to the monitoring chain using an LUT or dedicated processor before the frame reaches the director or DP's monitor.
Tip 3: Anamorphic lenses do not have the same minimum focus distance as their spherical equivalents. A 50mm anamorphic lens often has a minimum focus distance of 0.9-1.2 meters, compared to 0.3-0.5 meters for a spherical 50mm. On cramped interior setups where the working distance is less than 1 meter, confirm the minimum focus distance of your specific anamorphic lens before the scout. This affects which scenes can be shot anamorphic versus spherical.
Frequently Asked Questions
What is the difference between optical anamorphic and digital anamorphic?
Optical anamorphic uses a cylindrical lens element to physically squeeze the image before it reaches the sensor. Digital anamorphic (sometimes called "fake anamorphic") applies a digital crop or reframe in-camera or in post to simulate a widescreen ratio from a spherical lens, often adding a lens flare effect digitally. Digital anamorphic produces a widescreen image but does not create the characteristic anamorphic optical properties: oval bokeh, horizontal lens flares, and the distinctive focus falloff of genuine anamorphic optics. Optical anamorphic is required to achieve the genuine look.
Why do anamorphic lenses produce oval bokeh?
The cylindrical element that squeezes the horizontal dimension also affects the shape of out-of-focus highlights. Spherical lenses produce circular bokeh because the aperture diaphragm is circular and the light passes through a uniform optical path. Anamorphic lenses compress light horizontally, which elongates the circular out-of-focus spots vertically. At 2x squeeze, the bokeh is approximately twice as tall as it is wide. This oval shape is one of the most recognizable visual signatures of anamorphic photography and is considered desirable in certain genres.
Can I use a 2x anamorphic adapter on a spherical lens?
Yes. Anamorphic adapters (like the Sirui, Moment, or DJI anamorphic adapters) attach to the front of a spherical lens and add the squeeze optically. The quality varies significantly between adapters, and cheaper adapters introduce optical aberrations (soft edges, breathing on focus pulls). For professional production use, purpose-built anamorphic primes or zooms designed for the specific mount and sensor produce significantly better results than front-of-lens adapters. The aspect ratios in film post covers how different capture ratios affect the look and feel of the finished image.
What desqueeze setting should I use in DaVinci Resolve?
In the Media Pool, right-click on the anamorphic clip and select "Clip Attributes." Under the "Source Format" section, find the "Pixel Aspect Ratio" or "Anamorphic Desqueeze" option and enter the squeeze factor (1.33x, 2.0x, etc.). Resolve will then display the desqueezed image throughout the timeline. Alternatively, use a custom input resolution that accounts for the squeeze. For a 2x squeeze clip recorded at 2048 x 1080, set the timeline resolution to 4096 x 1080 to display it correctly. Always confirm the desqueeze setting before beginning the edit.
Related Tools
The Anamorphic Desqueeze Calculator takes sensor aspect ratio and squeeze factor as inputs and returns the final desqueezed aspect ratio. The Field of View Calculator includes an anamorphic squeeze input to calculate the actual horizontal field of view captured by a given anamorphic focal length. The Aspect Ratio Calculator handles the final delivery framing decisions once the desqueezed image is confirmed.
Conclusion
Anamorphic squeeze is a specific number that must be passed from the lens order through the camera report to post. It is not a creative variable to be resolved after the fact -- it is the technical specification that tells the colorist and editor what they're actually looking at. Calculate the output aspect ratio before the shoot using the sensor and squeeze factor. Confirm the result with a test chart. Put it in the camera report. The post team that receives correctly specified squeezed footage starts the edit on day one. The one that doesn't loses two days tracking down a number that should have been in the paperwork from the beginning. What was the most unusual anamorphic squeeze factor you've worked with, and what sensor did you put it on?
