What it frames
The Canon EOS 850D with the Canon EF 180mm f/3.5L Macro USM, 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. 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.
180mm on the Canon EOS 850D frames 1.86 m × 1.24 m at 15 m: like 288mm on full frame, 7.1° across.
The numbers
- Frame at 15 m1.86 m × 1.24 m
- Full-frame equivalent288mm
- Angle of view7.1° × 4.7°, 8.5° diagonal
- Depth of field at f/3.514.6 m to 15.4 m (86 cm)
- Depth of field at f/814.1 m to 16.1 m (1.97 m)
- Hyperfocal at f/3.5518 m
- Hyperfocal at f/8227 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.