What it frames
The Canon EOS 850D with the Canon EF 75-300mm f/4-5.6 III, over a 1.75 m person in front of a wall with a window. 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.
75mm on the Canon EOS 850D frames 45 cm × 30 cm at 1.5 m: like 120mm on full frame, 17° across.
The numbers
- Frame at 1.5 m45 cm × 30 cm
- Full-frame equivalent120mm
- Angle of view17° × 11°, 20° diagonal
- Depth of field at f/41.47 m to 1.53 m (5.4 cm)
- Depth of field at f/81.45 m to 1.56 m (11 cm)
- Hyperfocal at f/478.7 m
- Hyperfocal at f/839.4 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.