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What it frames

The Sony a7R VI with the Tamron 17-50mm f/4 Di III VXD, 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.

17mm on the Sony a7R VI frames 42.4 m × 28.2 m at 20 m: like 17mm on full frame, 93° across.

24mm eq.50mm eq.135mm eq.17mm · like 17mm on full frame42.4 m × 28.2 m at 20 m
The subject is 20 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 20 m42.4 m × 28.2 m
  • Full-frame equivalent17mm
  • Angle of view93° × 70°, 104° diagonal
  • Depth of field at f/42.23 m to infinity (to infinity)
  • Depth of field at f/81.18 m to infinity (to infinity)
  • Hyperfocal at f/42.52 m
  • Hyperfocal at f/81.27 m
  • Circle of confusion0.029 mm
f/42.23 m to infinity (everything to infinity)f/81.18 m to infinity (everything to infinity)camerasubject, 20 m40 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.