What it frames
The OM System PEN with the OM System M.Zuiko 90mm f/3.5 Macro IS PRO, 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 Micro Four Thirds sensor (17.3 x 13 mm) has a crop factor of 2, so the dashed frames are marked with the focal length that gives the same view on it.
90mm on the OM System PEN frames 2.88 m × 2.17 m at 15 m: like 180mm on full frame, 11° across.
The numbers
- Frame at 15 m2.88 m × 2.17 m
- Full-frame equivalent180mm
- Angle of view11° × 8.3°, 14° diagonal
- Depth of field at f/3.513.7 m to 16.5 m (2.81 m)
- Depth of field at f/812.4 m to 19 m (6.67 m)
- Hyperfocal at f/3.5161 m
- Hyperfocal at f/870.3 m
- Circle of confusion0.014 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.