cst1 likes camerasAsk a question

What it frames

The Canon EOS R8 Mark II with the Canon RF 800mm f/11 IS STM, 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.

800mm on the Canon EOS R8 Mark II frames 68 cm × 45 cm at 15 m: like 800mm on full frame, 2.6° across.

24mm eq.50mm eq.135mm eq.800mm · like 800mm on full frame68 cm × 45 cm 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 m68 cm × 45 cm
  • Full-frame equivalent800mm
  • Angle of view2.6° × 1.7°, 3.1° diagonal
  • Depth of field at f/1114.9 m to 15.1 m (21 cm)
  • Hyperfocal at f/112018 m
  • Circle of confusion0.029 mm
f/1114.9 m to 15.1 m (21 cm)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.