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What it frames

The Nikon D780 with the Nikon AF-S 300mm f/4E PF ED VR, over a 30 cm bird on a 1 m fence post. 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.

300mm on the Nikon D780 frames 1.8 m × 1.2 m at 15 m: like 300mm on full frame, 6.9° across.

24mm eq.50mm eq.135mm eq.300mm · like 300mm on full frame1.8 m × 1.2 m at 15 m
The subject is 15 m away; things behind it are drawn smaller, as the camera sees them.
Inside the frame: the picture you would get.

The numbers

  • Frame at 15 m1.8 m × 1.2 m
  • Full-frame equivalent300mm
  • Angle of view6.9° × 4.6°, 8.2° diagonal
  • Depth of field at f/414.7 m to 15.3 m (57 cm)
  • Depth of field at f/814.5 m to 15.6 m (1.13 m)
  • Hyperfocal at f/4780 m
  • Hyperfocal at f/8390 m
  • Circle of confusion0.029 mm
f/414.7 m to 15.3 m (57 cm)f/814.5 m to 15.6 m (1.13 m)camerasubject, 15 m30 m
Depth of field: what is acceptably sharp, wide open and at f/8, focused on the subject.

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.