Focal Length ↔ Field of View Calculator
Focal length in, angle of view out, or the other way round. Any sensor. Then open a grid at exactly that lens.
Focal length and field of view
Focal length on its own does not tell you how wide a picture is; it has to be paired with the size of the sensor or film. The relationship is FOV = 2 · atan(sensor size ⁄ (2 · focal length)), applied separately to the sensor's width, height and diagonal. That is why the same 35 mm lens is a moderate wide-angle on a full-frame camera and a normal lens on APS-C.
The 35 mm-equivalent focal length is the focal length that would give the same diagonal angle on a full-frame (36 × 24 mm) sensor. It is the number everyone uses to compare lenses across cameras, and it is the number the perspective grids on this site use: set a grid to 24 mm and it shows what a 24 mm-equivalent lens sees.
Using it for drawing
Perspective drawings do not have sensors, but they do have a picture width and a distance from the eye to the picture plane, which is the same ratio. A 50 mm lens means the eye is 1.39 picture-widths back from the picture; a 24 mm lens means 0.75 widths. Wide lenses put the vanishing points close to the frame and make near things loom; long lenses push the points out and flatten the scene. If you want a drawing to feel like a photograph taken with a particular lens, this calculator gives the angle and the grid tools draw it.
Common lenses at a glance
| Lens (35 mm equiv.) | Horizontal FOV | Feel | |---|---|---| | 14 mm | 104° | extreme wide, edges stretch; consider the curvilinear grid | | 24 mm | 74° | dramatic architecture, interiors, street | | 35 mm | 54° | reportage; close to a relaxed human field of attention | | 50 mm | 40° | "normal"; comfortable for figures and rooms | | 85 mm | 24° | portraits; flattened perspective | | 200 mm | 10° | compressed; almost parallel projection |
Questions
What is the field of view of a 50 mm lens?
On a full-frame camera, about 39.6° horizontally, 27° vertically and 46.8° diagonally. On APS-C (1.5× crop) the same lens gives about 26.6° horizontally, which is what a 75 mm lens gives on full frame.
Which field of view do the grid tools use?
Horizontal. When a grid shows 50°, that is the angle across the width of the picture, which corresponds to a 38 mm lens on full frame.
Why do lens makers quote a different angle?
They usually quote the diagonal, which is always the largest of the three. A 24 mm lens is 84° diagonal but 74° horizontal.
How do I find the field of view of my phone?
Most phone main cameras are 24–26 mm equivalent, about 70–74° horizontal. Ultrawides are 13–16 mm equivalent (100–110°). Choose the phone sensor preset and type the real focal length from the photo's EXIF data, or pick full frame and type the equivalent.