Camera Sensor FOV Calculator Formula

Understand the math behind the camera sensor fov calculator. Each variable explained with a worked example.

Use the Camera Sensor FOV Calculator

Formulas Used

Field of View

fov_deg = 2 * atan(sensor_size / (2 * focal_length)) * 180 / pi

FOV (arcmin)

fov_arcmin = 2 * atan(sensor_size / (2 * focal_length)) * 180 / pi * 60

Variables

VariableDescriptionDefault
sensor_sizeSensor Dimension(mm)23.5
focal_lengthFocal Length(mm)1000

How It Works

Camera Sensor Field of View

The angular field of view determines how much sky the sensor captures.

Formula

FOV = 2 arctan(d / 2f)

  • *d* = sensor dimension (width or height) in mm
  • *f* = telescope focal length in mm

    • Convert from radians to degrees by multiplying by 180/pi.

    Worked Example

    APS-C sensor (23.5 mm width) on a 1000 mm focal-length scope.

    sensor_size = 23.5focal_length = 1000
    1. 01FOV = 2 * atan(23.5 / 2000)
    2. 02FOV = 2 * atan(0.01175)
    3. 03FOV = 2 * 0.01175 rad = 0.02349 rad
    4. 04FOV = 0.02349 * 180 / pi = 1.346 degrees

    Frequently Asked Questions

    Should I use sensor width or height?

    Calculate both. The width gives the horizontal FOV, the height gives vertical FOV. The diagonal gives the total angular coverage.

    How does a focal reducer affect FOV?

    A focal reducer shortens the effective focal length, widening the FOV. A 0.63x reducer on a 1000 mm scope gives 630 mm effective.

    What FOV is ideal for deep-sky imaging?

    It depends on the target. Large nebulae need a wide FOV (over 1 degree); small galaxies and planetary nebulae suit narrow FOVs (under 0.5 degrees).

    Ready to run the numbers?

    Open Camera Sensor FOV Calculator