thumb|Average binocular horizontal FOV for humans

thumb|Average vertical FOV of the human eye

right|thumb|Angle of view can be measured horizontally, vertically, or diagonally. Image may show non-aligned lines.

The field of view (FOV) is the angular extent of the observable world that is seen at any given moment. In the case of optical instruments or sensors, it is a solid angle through which a detector is sensitive to electromagnetic radiation. It is further relevant in photography.

Humans and animals

In the context of human and primate vision, the term "field of view" is typically only used in the sense of a restriction to what is visible by external apparatus, like when wearing spectacles or virtual reality goggles. Note that eye movements are allowed in the definition but do not change the field of view when understood this way.

If the analogy of the eye's retina working as a sensor is drawn upon, the corresponding concept in human (and much of animal vision) is the visual field. It is defined as "the number of degrees of visual angle during stable fixation of the eyes". Note that eye movements are excluded in the visual field's definition. Humans have a slightly over 210-degree forward-facing horizontal arc of their visual field (i.e. without eye movements), (with eye movements included it is slightly larger, as you can try for yourself by wiggling a finger on the side), while some birds have a complete or nearly complete 360-degree visual field. The vertical range of the visual field in humans is around 150 degrees. the remaining ~50 degrees on each side Single pixel IFOV is closely related to concept of ground resolved distance, ground sample distance, modulation transfer function, and resolved pixel size.

Astronomy

In astronomy, the field of view is usually expressed as an angular area viewed by the instrument, in square degrees, or for higher magnification instruments, in square arc-minutes. For reference the Wide Field Channel on the Advanced Camera for Surveys on the Hubble Space Telescope has a field of view of 10 sq. arc-minutes, and the High Resolution Channel of the same instrument has a field of view of 0.15 sq. arc-minutes. Ground-based survey telescopes have much wider fields of view. The photographic plates used by the UK Schmidt Telescope had a field of view of 30 sq. degrees. The 1.8 m (71 in) Pan-STARRS telescope, with the most advanced digital camera to date has a field of view of 7 sq. degrees. In the near infra-red WFCAM on UKIRT has a field of view of 0.2 sq. degrees and the VISTA telescope has a field of view of 0.6 sq. degrees. Until recently digital cameras could only cover a small field of view compared to photographic plates, although they beat photographic plates in quantum efficiency, linearity and dynamic range, as well as being much easier to process.

Photography

In photography, the field of view is that part of the world that is visible through the camera at a particular position and orientation in space; objects outside the FOV when the picture is taken are not recorded in the photograph. It is most often expressed as the angular size of the view cone, as an angle of view. For a normal lens focused at infinity, the diagonal (or horizontal or vertical) field of view can be calculated as:

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:<math>\mathrm{FOV} = 2 \times \arctan\left(\frac{s}{2f}\right)</math>

Where:

  • <math>s</math> is the sensor size (diagonal, width, or height);
  • <math>f</math> is the focal length of the lens.

Microscopy

thumb|Field of view diameter in microscopy

In microscopy, the field of view in high power (usually a 400-fold magnification when referenced in scientific papers) is called a high-power field, and is used as a reference point for various classification schemes.

For an objective with magnification <math>m</math>, the FOV is related to the Field Number (FN) by

:<math>\mathrm{FOV} = \frac{\mathrm{FN{m},</math>

if other magnifying lenses are used in the system (in addition to the objective), the total <math>m</math> for the projection is used.

Video games

The field of view in video games refers to the field of view of the camera looking at the game world, which is dependent on the scaling method used.

See also

  • Field of regard
  • Panorama
  • Perimetry
  • Peripheral vision
  • Visual perception
  • Useful field of view
  • 35 mm equivalent focal length
  • Angle of view
  • Crop factor
  • Image sensor format
  • Line of sight

References