Canon APS-C crop factor and field of view calculator
A Canon APS-C sensor measures 22.3 by 14.9 mm, a diagonal of 26.82 mm. Against the full-frame diagonal of 43.27 mm that is a crop factor of 1.613.
The diagonal divided by this gives the acceptable blur circle. 1500 is the usual modern figure.
- Full-frame equivalent focal length
- 56.46
- Equivalent aperture for depth of field
- 4.517
- Sensor diagonal
- 26.820
- Sensor area
- 332.27 mm2
- Full frame gathers this many times more light
- 2.600
- Horizontal field of view
- 35.341 degrees
- Vertical field of view
- 24.033 degrees
- Diagonal field of view
- 41.928 degrees
- Hyperfocal distance
- 24 504
- Depth of field
- 737
- Frame width at the subject
- 1.911
Show the working
- Focal length = 35
- Aperture f-number = 2.8
- Subject distance = 3
- Circle of confusion divisor = 1500
- sensor_w = 22.3 = 22.3
- sensor_h = 14.9 = 14.9
- Sensor diagonal = hypot(22.3, 14.9) = 26.8198
- Crop factor = 26.8198 > 0 ? 43.266615305567875 / 26.8198 : 0 = 1.613 24
- Full-frame equivalent focal length = 35 * 1.613 24 = 56.4633
- Equivalent aperture for depth of field = 2.8 * 1.613 24 = 4.517 06
- Sensor area = 22.3 * 14.9 = 332.27
- Full frame gathers this many times more light = 332.27 > 0 ? 864 / 332.27 : 0 = 2.600 29
- Horizontal field of view = deg(2 * atan(22.3 / (2 * 35))) = 35.3408
- Vertical field of view = deg(2 * atan(14.9 / (2 * 35))) = 24.033
- Diagonal field of view = deg(2 * atan(26.8198 / (2 * 35))) = 41.9276
- coc = 26.8198 / 1500 = 0.017 879 8
- Hyperfocal distance = 35^2 / (2.8 * 0.017 879 8) + 35 = 24 503.9
- near = 3*1000 * 24 503.9 / (24 503.9 + (3*1000 - 35)) = 2676.18
- far = 3*1000 < 24 503.9 ? 3*1000 * 24 503.9 / (24 503.9 - (3*1000 - 35)) : 1e9 = 3412.97
- Depth of field = 3412.97 >= 1e9 ? 1e9 : 3412.97 - 2676.18 = 736.795
- Frame width at the subject = 35 > 0 ? 3 * 22.3 / 35 : 0 = 1.911 43
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 Canon APS-C
| Lens | Full-frame equivalent |
|---|---|
| 12 mm | 19.4 mm |
| 16 mm | 25.8 mm |
| 24 mm | 38.7 mm |
| 35 mm | 56.5 mm |
| 50 mm | 80.7 mm |
| 85 mm | 137.1 mm |
| 135 mm | 217.8 mm |
| 200 mm | 322.6 mm |
Frequently asked
What is the crop factor of a Canon APS-C sensor?
1.613, calculated from its 26.82 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.