Introduction
The rental house calls to say the ALEXA Mini LF you reserved is down for sensor repair. They're offering an ALEXA Mini (Super 35) as a replacement. Your entire lens package was chosen for Full Frame coverage. Before you panic, you need one number: the crop factor between the two sensors, and what it means for every focal length on your shot list.
The crop factor comparison table shows you exactly how the same lens behaves across every common sensor size in cinema and photography. Enter a focal length and instantly see the equivalent field of view, crop factor, and horizontal angle for each sensor. No more mental math when switching camera bodies mid-production.
This tool lives at the intersection of pre-production planning and on-set problem solving. Whether you're building a lens package from scratch or adapting to a last-minute camera swap, the comparison table gives you the numbers you need at a glance.
What This Tool Calculates
The calculator takes one input: the actual focal length of the lens in millimeters. It displays a visual bar chart showing relative sensor areas and a detailed table for each sensor format.
For each sensor, the table shows the sensor dimensions in millimeters, the crop factor relative to Full Frame, the equivalent focal length (the focal length on Full Frame that would produce the same field of view), the horizontal field of view in degrees, and example cameras that use that sensor format.
The Formula and How It Works
Crop factor is the ratio of the Full Frame sensor diagonal to the target sensor's diagonal. The Full Frame diagonal is 43.27mm (from a 36mm by 24mm sensor). For any other sensor: Crop Factor = 43.27 / sensor diagonal.
The equivalent focal length equals the actual focal length multiplied by the crop factor. A 35mm lens on a Super 35 sensor (crop factor 1.45x) has an equivalent focal length of 35 times 1.45 = 50.75mm. This means the 35mm lens on Super 35 produces the same field of view as a 50.75mm lens on Full Frame.
Horizontal field of view uses the rectilinear formula: HFoV = 2 times arctan(sensor width / (2 times focal length)), expressed in degrees.
Worked example: a 50mm lens on Micro Four Thirds (17.3mm by 13mm sensor). Sensor diagonal = sqrt(17.3 squared + 13 squared) = 21.64mm. Crop factor = 43.27 / 21.64 = 2.0x. Equivalent FL = 50 times 2.0 = 100mm. The 50mm lens on MFT frames like a 100mm on Full Frame.
Real-World Examples
Camera Swap from Full Frame to Super 35 Mid-Production
When a Sony VENICE developed a sensor issue on day 3 of a 20-day shoot, the crew switched to a Sony FX9 (Super 35). The DP had planned all shots around Full Frame coverage. Using the comparison table with a 35mm focal length, the team saw the Full Frame shot (35mm, 54.4-degree HFoV) would become a 50.75mm equivalent on Super 35 (39.2-degree HFoV). They swapped the 35mm for a 24mm lens on the FX9, which produced a 54.8-degree HFoV and closely matched the original framing.
Building a Lens Package for Multi-Camera Documentary
A documentary production shooting on both a Full Frame Sony FX3 and an APS-C Sony FX30 needed matching wide, mid, and tight lenses for each body. The comparison table showed that a 24mm on Full Frame required a 16mm on APS-C for a match. For the mid (50mm FF), a 35mm worked on APS-C. For the tight (85mm FF), a 56mm was closest on APS-C. The producer ordered the correct rental package in one pass.
Drone Lens Selection for IMAX Delivery
A VFX supervisor planning aerial plates for an IMAX sequence needed to match the field of view of the main unit's 24mm lens on an ALEXA 65 (Large Format, 0.67x crop) with a DJI Inspire 3 (Full Frame). The comparison showed the ALEXA 65 at 24mm produced an HFoV of 96.3 degrees. On Full Frame, a 17mm lens was needed to approximate that angle. The supervisor rented the DJI 18mm DL lens as the closest available match.
Sensor Formats Used in Common Cinema Cameras
| Format | Width (mm) | Crop Factor | Example Cameras |
|---|---|---|---|
| Large Format | 54.12 | 0.67x | ARRI ALEXA 65 |
| Full Frame | 36.00 | 1.00x | ALEXA Mini LF, Sony VENICE |
| ALEXA 35 | 27.99 | 1.29x | ARRI ALEXA 35 |
| Super 35 | 24.89 | 1.45x | ALEXA Mini, AMIRA |
| APS-C (Sony) | 23.50 | 1.53x | Sony a6700, FX30 |
| APS-C (Canon) | 22.30 | 1.61x | Canon R7, C70 |
| Micro Four Thirds | 17.30 | 2.00x | GH6, BMPCC 4K |
| Super 16mm | 12.52 | 2.88x | BMPCC, Bolex |
Pro Tips and Common Mistakes
Pro Tips
- Keep a printed crop factor card in your camera case. When someone hands you an unfamiliar body, multiply your planned focal length by the crop factor to know instantly what field of view you'll get.
- Crop factor affects more than field of view. A 1.5x crop sensor with a 50mm lens at f/2 produces the DoF equivalent of a 75mm at f/3 on Full Frame. Factor this into your shallow DoF decisions when switching sensors.
- When comparing cameras for a multi-cam shoot, match on field of view (degrees), not focal length. A 35mm on Super 35 and a 50mm on Full Frame produce nearly identical framing.
- Large format sensors (ALEXA 65, RED MONSTRO) have crop factors below 1.0x. A 50mm on Large Format is wider than 50mm on Full Frame. This is why LF cinematography often uses longer focal lengths.
Common Mistakes
- Applying crop factor to the aperture for exposure calculations. Crop factor changes field of view and depth of field equivalence, but it does not change the amount of light reaching the sensor. An f/2.8 lens transmits the same light on any sensor size.
- Confusing equivalent focal length with actual focal length for lens rental. If you need a 50mm Full Frame equivalent on Super 35, you rent a 35mm lens, not a 50mm.
- Assuming all Super 35 sensors are identical. The ARRI ALEXA 35 has a 27.99mm wide sensor, while the ALEXA Mini uses 24.89mm. That's a 12 percent difference in crop factor that shifts every focal length calculation.
Frequently Asked Questions
What is crop factor?
Crop factor describes how much smaller a sensor is compared to Full Frame (36mm by 24mm). A crop factor of 1.5x means the sensor diagonal is 1.5 times smaller than Full Frame. This makes lenses appear to reach further: a 50mm lens on a 1.5x crop sensor frames like a 75mm lens on Full Frame.
Does crop factor affect depth of field?
Indirectly, yes. A smaller sensor requires a shorter focal length to match the field of view of a larger sensor. That shorter focal length produces deeper depth of field. A 35mm at f/2.8 on Super 35 has deeper DoF than a 50mm at f/2.8 on Full Frame, even though framing is similar.
How do I match lenses between two different camera bodies?
Divide the Full Frame equivalent focal length by the target sensor's crop factor. If you want a 50mm Full Frame look on APS-C (1.5x crop), use a 33mm lens (50 / 1.5). If no 33mm exists, a 35mm is the closest standard option.
Can I use Full Frame lenses on a Super 35 camera?
Yes, as long as the lens mount is compatible. Full Frame lenses project an image circle large enough to cover the smaller Super 35 sensor. The camera uses the center portion. You lose wide-angle coverage but gain potentially sharper performance from the center of the lens.
Start Calculating
Crop factor is the universal translator between sensor sizes. Whether you're swapping cameras, building a multi-cam package, or evaluating a new system, the comparison table gives you the numbers that keep every shot consistent.
Enter your go-to focal length above and see how it translates across every major sensor format. What sensor size do you shoot on most, and have you ever been caught off guard by a crop factor mismatch?
