What it frames
The Nikon D780 with the Zeiss Milvus 18mm f/2.8, over an 8.5 m tree and a 1.75 m person, with hills behind. 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.
18mm on the Nikon D780 frames 40 m × 26.7 m at 20 m: like 18mm on full frame, 90° across.
The numbers
- Frame at 20 m40 m × 26.7 m
- Full-frame equivalent18mm
- Angle of view90° × 67°, 100° diagonal
- Depth of field at f/2.83.34 m to infinity (to infinity)
- Depth of field at f/81.31 m to infinity (to infinity)
- Hyperfocal at f/2.84.03 m
- Hyperfocal at f/81.42 m
- Circle of confusion0.029 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.