Micro Four Thirds crop factor and field of view calculator
A Micro Four Thirds sensor measures 17.3 by 13 mm, a diagonal of 21.64 mm. Against the full-frame diagonal of 43.27 mm that is a crop factor of 1.999.
The diagonal divided by this gives the acceptable blur circle. 1500 is the usual modern figure.
- Full-frame equivalent focal length
- 69.98
- Equivalent aperture for depth of field
- 5.598
- Sensor diagonal
- 21.640
- Sensor area
- 224.90 mm2
- Full frame gathers this many times more light
- 3.842
- Horizontal field of view
- 27.764 degrees
- Vertical field of view
- 21.042 degrees
- Diagonal field of view
- 34.357 degrees
- Hyperfocal distance
- 30 361
- Depth of field
- 592
- Frame width at the subject
- 1.483
Show the working
- Focal length = 35
- Aperture f-number = 2.8
- Subject distance = 3
- Circle of confusion divisor = 1500
- sensor_w = 17.3 = 17.3
- sensor_h = 13 = 13
- Sensor diagonal = hypot(17.3, 13) = 21.64
- Crop factor = 21.64 > 0 ? 43.266615305567875 / 21.64 : 0 = 1.999 38
- Full-frame equivalent focal length = 35 * 1.999 38 = 69.9783
- Equivalent aperture for depth of field = 2.8 * 1.999 38 = 5.598 27
- Sensor area = 17.3 * 13 = 224.9
- Full frame gathers this many times more light = 224.9 > 0 ? 864 / 224.9 : 0 = 3.841 71
- Horizontal field of view = deg(2 * atan(17.3 / (2 * 35))) = 27.7641
- Vertical field of view = deg(2 * atan(13 / (2 * 35))) = 21.0416
- Diagonal field of view = deg(2 * atan(21.64 / (2 * 35))) = 34.3573
- coc = 21.64 / 1500 = 0.014 426 7
- Hyperfocal distance = 35^2 / (2.8 * 0.014 426 7) + 35 = 30 360.8
- near = 3*1000 * 30 360.8 / (30 360.8 + (3*1000 - 35)) = 2733.09
- far = 3*1000 < 30 360.8 ? 3*1000 * 30 360.8 / (30 360.8 - (3*1000 - 35)) : 1e9 = 3324.69
- Depth of field = 3324.69 >= 1e9 ? 1e9 : 3324.69 - 2733.09 = 591.596
- Frame width at the subject = 35 > 0 ? 3 * 17.3 / 35 : 0 = 1.482 86
Values are shown to six significant figures here; the arithmetic itself runs on exact fractions and is only rounded where a number is printed.
Scenarios & local history
Compare a saved scenario
Recent calculations
The formula
- crop factor = full-frame diagonal / sensor diagonal
- field of view = 2 arctan(sensor dimension / 2 focal length)
- hyperfocal distance = f^2 / (N c) + f
- equivalent aperture = aperture x crop factor, for depth of field and total light
Crop factor changes the framing, not the lens. A 50 mm lens is always a 50 mm lens; it just sees a smaller rectangle.
Equivalent aperture matters for depth of field and total light gathered, not for exposure. An f/2.8 lens meters as f/2.8 on any format.
The circle of confusion is a judgement about acceptable sharpness at a viewing size, not a physical constant.
Equivalent focal lengths on Micro Four Thirds
| Lens | Full-frame equivalent |
|---|---|
| 12 mm | 24.0 mm |
| 16 mm | 32.0 mm |
| 24 mm | 48.0 mm |
| 35 mm | 70.0 mm |
| 50 mm | 100.0 mm |
| 85 mm | 169.9 mm |
| 135 mm | 269.9 mm |
| 200 mm | 399.9 mm |
Frequently asked
What is the crop factor of a Micro Four Thirds sensor?
1.999, calculated from its 21.64 mm diagonal against full frame at 43.27 mm.
Does a crop sensor make a lens longer?
No. The lens projects the same image; the smaller sensor simply records a smaller part of it, which looks like a longer lens.