Campo de Visão (FOV)

Field of view: lens and sensor geometry

The field of view (FOV) is how wide an angle, in degrees, a lens sees on a given sensor. You get it from FOV = 2 · arctan(d / (2·f)), where d is the sensor dimension you care about (horizontal, vertical or diagonal) and f is the focal length. Take a full-frame sensor, 36 mm across. A 50 mm normal lens covers roughly 39.6° horizontally. Drop to a 24 mm wide and you jump to 73.7°; reach for a 200 mm tele and it narrows to just 10.3°. A fisheye, meanwhile, can swallow 180° or more. Shrink the sensor and the same focal length sees less. That is the crop factor at work: APS-C ≈ 1.5×, MFT = 2×, which is why a 50 mm on APS-C frames about like a 75 mm on full-frame.

Applications

Planning shots and storyboards. Picking the right lens — wide for landscapes and cramped interiors, tele for wildlife and sports. VR/AR capture, where a 180° fisheye gets you immersive content. And working out security camera coverage, so you know how much of a room or street one lens will actually catch.

FAQ

Why does my 50 mm look tighter on APS-C than full-frame? The smaller sensor only uses the middle of the image circle, so you end up with a narrower angle even though the focal length hasn't changed.

Horizontal, vertical or diagonal FOV — which one matters? Whichever fits the job. Horizontal tells you framing width, vertical tells you how much ceiling or sky you'll get, and diagonal is the biggest number, which is the one marketing tends to quote.

Does the formula work for fisheye lenses? Roughly, not exactly. Fisheyes use non-rectilinear projections such as equidistant or equisolid, and against those the plain 2·arctan formula comes out low compared with the real FOV.