In short: Field of view is the angle a lens sees across the sensor. Use 2 × arctan(sensor width ÷ (2 × focal length)). A 50 mm lens on a 36 mm full-frame sensor sees about 39.6 degrees across. On a sensor 22.2 mm wide it sees about 25 degrees. To find the width of frame at a distance, multiply the distance by the sensor width and divide by the focal length.
What the calculator tells you
It tells you how much of the set a lens will take in, before anyone carries the camera onto the cove. Enter the sensor width, the focal length and the distance to the subject. It returns the horizontal angle and the width of the frame at that distance.
The formula
The horizontal angle of view is:
angle = 2 × arctan(sensor width ÷ (2 × focal length))
Both numbers go in millimetres. The width of the frame at a given subject distance is:
frame width = subject distance × sensor width ÷ focal length
Sensor widths to check
Check the sensor width in the camera's specification, not the name of the format. The same name covers slightly different sizes.
| Format | Width (mm) | Notes |
|---|---|---|
| Full frame 35 mm | 35.8 to 36 | The 36 mm figure is the usual one quoted |
| Super 35 motion picture | 24.89 | Width of the 4-perf film frame, 18.66 mm tall. A 16:9 digital Super 35 sensor is about 14 mm tall, so use Custom |
| APS-C | 22.2 to 23.7 | Varies by maker |
| Micro Four Thirds | 17.3 | Common on small cameras |
| Super 16 | 12.52 | Small film format, rarely used now |
A worked example
A 50 mm lens on a 36 mm full-frame sensor:
- Divide 36 by twice 50, which is 0.36.
- Take the arctangent, about 19.8 degrees.
- Double it: about 39.6 degrees across the frame.
Now the same lens on a 22.2 mm APS-C sensor gives about 25 degrees. The lens has not changed. The sensor has.
To see how that changes the set, take a subject 3 metres from the lens. On full frame the frame is 36 × 3 ÷ 50 = 2.16 metres wide at that distance. A 5.3 metre cove is therefore much wider than one frame at 3 metres, and the calculator tells you how far back the camera needs to be to fit it.
Common mistakes
- Using the full-frame width for a camera that records a cropped area. Some cameras crop the sensor in certain recording modes, so check the mode you will shoot in.
- Quoting a crop factor as if it were a change in focal length. A 50 mm lens on a 1.6 times crop body frames like an 80 mm lens on full frame. The lens is still 50 mm.
- Forgetting that the formula gives the angle at infinity. For close subjects, the frame width formula is the one to use.
- Trusting the calculator without a test. Put the camera where the calculator says and check the monitor with the actor on the mark.
Using it with the other tools
Once you have the frame, the depth of field depends on the same lens and distance. Use the depth of field calculator next. For the lighting that fills the frame, see three-point lighting and beyond.
Sources
- Wikipedia, Angle of view, read 5 November 2026
- Wikipedia, Image sensor format, read 5 November 2026
Related guides
- Depth of field calculator, with a worked example
- Data rate and storage calculator for camera files
- Frame rates and shutter: the 180 degree rule and flicker-free shutters for UK 50Hz
- Lens and sensor crop cheat sheet
- Camera report template: what to log on each take
- All guides and tools
The picture at the top of this page is an illustration, not a photograph of a client or a real job.
Questions we get asked
How do I work out the field of view of a lens?
Divide the sensor width by twice the focal length, take the arctangent, then double the result: 2 × arctan(sensor width ÷ (2 × focal length)).
Is a 50 mm lens the same on every camera?
The focal length is the same but the picture is not. A smaller sensor records a narrower view from the same lens, so a 50 mm lens behaves like a longer lens on a smaller sensor.
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