OpenCameraLab

Field of View Calculator

Find the angle of view for a sensor and focal length, and how much it covers.

Results

Horizontal angle of view
39.6°

How wide a slice of the scene the frame captures left to right.

Vertical angle of view
27.0°

How tall a slice of the scene the frame captures, top to bottom.

Diagonal angle of view
46.8°

The angle of view measured corner to corner, often used to compare lenses across formats.

Frame width at subject distance
7.20 m

How wide a scene the frame covers at the subject distance you entered.

How it works

Field of view describes how much of the world lands in the frame. It depends on two things only: the focal length of the lens and the physical size of the sensor behind it. A 50mm lens is a normal lens on full frame, a short telephoto on APS-C, and a wide angle on medium format, because the sensor crops a different slice of the same projected image.

The frame width figure turns the angle into something you can act on. If you need to photograph a three-metre-wide group from five metres back, that tells you directly whether your lens covers it.

Manufacturers usually quote the diagonal angle, which is the largest of the three and sounds the most impressive. The horizontal figure is closer to what people mean when they describe how wide a shot feels.

The formula

angle = 2 × arctan(sensor dimension / (2 × f))

Applied separately to the sensor width, height, and diagonal. Frame width at a distance d is 2 × d × tan(horizontal angle / 2).

Frequently asked questions

Why does my 50mm look different on two cameras?
The lens projects the same image either way; the sensor decides how much of it gets recorded. A smaller sensor keeps a smaller central portion, which reads as a narrower, more telephoto view.
Does field of view change when I focus closer?
Slightly, yes. The standard formula assumes focus at infinity. Focusing close extends the lens and narrows the angle a little, an effect called focus breathing, which is pronounced on some lenses and negligible on others.
Which angle should I use when comparing lenses?
The diagonal if you are comparing across different aspect ratios, since it is least affected by frame shape. The horizontal if you are thinking about how a scene will actually be framed.

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