What it frames
The Canon EOS 850D with the Canon EF 28mm f/2.8 IS USM, over a 1.75 m person in a street, with a door, a parked car and buildings. Everything is drawn to scale: the solid frame is what the camera takes in, the dashed ones are 24, 50 and 135mm on full frame from the same spot. Its APS-C (Canon) sensor (22.3 x 14.9 mm) has a crop factor of 1.6, so the dashed frames are marked with the focal length that gives the same view on it.
28mm on the Canon EOS 850D frames 3.98 m × 2.66 m at 5 m: like 45mm on full frame, 43° across.
The numbers
- Frame at 5 m3.98 m × 2.66 m
- Full-frame equivalent45mm
- Angle of view43° × 30°, 51° diagonal
- Depth of field at f/2.83.8 m to 7.33 m (3.53 m)
- Depth of field at f/82.62 m to 53.8 m (51.2 m)
- Hyperfocal at f/2.815.7 m
- Hyperfocal at f/85.51 m
- Circle of confusion0.018 mm
How it is worked out
The frame at a distance is distance × sensor size ÷ focal length, across and up; the angle of view is 2 × atan(sensor size ÷ (2 × focal length)). Depth of field uses the thin-lens formulas: the hyperfocal distance H = f² ÷ (N × c) + f, the near limit s(H − f) ÷ (H + s − 2f) and the far limit s(H − f) ÷ (H − s), sharp to infinity from H on, with a circle of confusion c of the sensor diagonal ÷ 1500 and, on a zoom whose aperture changes, the maximum aperture taken linearly between its ends. These are for a rectilinear lens; a fisheye takes in more. Ask for this page with Accept: application/json for the numbers alone.