photo:fov

# angular field of view (FOV) or angle of view (AOV)

## introduction

• angular field of view is the viewable scene through your system measured as an angle
• human cone of visual attention is ~55deg which equates to a 43mm focal length lens on a 35mm full frame camera hence lenses with focal lengths in that vicinity are regarded as “standard lenses”

## camera lens angle of view

• angle of view in radians = 2 x arctan (d/2f) where d = size of dimension of sensor in mm and f = effective actual focal length in mm
• for telephoto lenses, this approximates to angle of view in degrees = (180/pi) * (d/f)
• effective focal length:
• for most photography, this is the actual focal length as stated for the lens
• for macrophotography, the effective focal length = actual focal length x (1+magnification factor), such that for a 1:2 macro, the magnification factor is 1.5
• for telescopes, effective focal length depends upon whether other elements are used and how they are used such as eyepieces and Barlow lenses
• as an example of subject size, apparent angle of the moon and sun is approx. 0.5 deg

## 35mm full frame camera systems

• sensor is 36mm x 24mm and a diagonal of 43.3mm
effective focal length horizontal fov vertical fov diagonal fov
50mm 39.6 27.0 46.8
100mm 19.8 13.5 23.4
200mm 9.9 6.75 11.7
300mm 6.6 4.5 7.8
400mm 4.95 3.38 5.85
500mm 3.96 2.7 4.48
1000mm 1.98 1.35 2.34
2000mm 1 0.68 1.17
5000mm 0.4 0.27 0.45

## Micro Four Thirds or Four Thirds cameras

• sensor size is 17.3 x 13.0mm and a diagonal of 21.63mm = half the diagonal size of a 35mm sensor hence the 2x “crop factor”
effective focal length equivalent focal length in 35mm system horizontal fov vertical fov diagonal fov
45mm 90mm 22 16.5 27.5
50mm 100mm 19.8 14.88 24.78
75mm 150mm 14.85 11.16 18.59
100mm 200mm 9.9 7.44 12.39
135mm 270mm 7.3 5.5 9.2