4x5 large format crop factor and field of view calculator
A 4x5 large format sensor measures 127 by 102 mm, a diagonal of 162.89 mm. Against the full-frame diagonal of 43.27 mm that is a crop factor of 0.266.
The diagonal divided by this gives the acceptable blur circle. 1500 is the usual modern figure.
- Full-frame equivalent focal length
- 9.30
- Equivalent aperture for depth of field
- 0.744
- Sensor diagonal
- 162.890
- Sensor area
- 12 954.00 mm2
- Full frame gathers this many times more light
- 0.067
- Horizontal field of view
- 122.275 degrees
- Vertical field of view
- 111.078 degrees
- Diagonal field of view
- 133.490 degrees
- Hyperfocal distance
- 4064
- Depth of field
- 9361
- Frame width at the subject
- 10.886
Show the working
- Focal length = 35
- Aperture f-number = 2.8
- Subject distance = 3
- Circle of confusion divisor = 1500
- sensor_w = 127 = 127
- sensor_h = 102 = 102
- Sensor diagonal = hypot(127, 102) = 162.89
- Crop factor = 162.89 > 0 ? 43.266615305567875 / 162.89 : 0 = 0.265 619
- Full-frame equivalent focal length = 35 * 0.265 619 = 9.296 68
- Equivalent aperture for depth of field = 2.8 * 0.265 619 = 0.743 734
- Sensor area = 127 * 102 = 12 954
- Full frame gathers this many times more light = 12 954 > 0 ? 864 / 12 954 : 0 = 0.066 697 5
- Horizontal field of view = deg(2 * atan(127 / (2 * 35))) = 122.275
- Vertical field of view = deg(2 * atan(102 / (2 * 35))) = 111.078
- Diagonal field of view = deg(2 * atan(162.89 / (2 * 35))) = 133.49
- coc = 162.89 / 1500 = 0.108 593
- Hyperfocal distance = 35^2 / (2.8 * 0.108 593) + 35 = 4063.8
- near = 3*1000 * 4063.8 / (4063.8 + (3*1000 - 35)) = 1734.49
- far = 3*1000 < 4063.8 ? 3*1000 * 4063.8 / (4063.8 - (3*1000 - 35)) : 1e9 = 11 095.2
- Depth of field = 11 095.2 >= 1e9 ? 1e9 : 11 095.2 - 1734.49 = 9360.67
- Frame width at the subject = 35 > 0 ? 3 * 127 / 35 : 0 = 10.8857
Values are shown to six significant figures here; the arithmetic itself runs on exact fractions and is only rounded where a number is printed.
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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 4x5 large format
| Lens | Full-frame equivalent |
|---|---|
| 12 mm | 3.2 mm |
| 16 mm | 4.2 mm |
| 24 mm | 6.4 mm |
| 35 mm | 9.3 mm |
| 50 mm | 13.3 mm |
| 85 mm | 22.6 mm |
| 135 mm | 35.9 mm |
| 200 mm | 53.1 mm |
Frequently asked
What is the crop factor of a 4x5 large format sensor?
0.266, calculated from its 162.89 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.