How to use the depth of field calculator
- Choose your camera's sensor size. This sets the circle of confusion, the largest blur spot that still looks sharp.
- Enter the actual focal length of the lens (not the "equivalent" focal length), the aperture, and the distance you focus at.
- Read the near and far limits of acceptable sharpness, the total depth of field, and the hyperfocal distance.
What affects depth of field
Depth of field is the zone in front of and behind your focus point that looks acceptably sharp. Three things control it: a wider aperture (smaller f-number) makes it shallower, a longer focal length makes it shallower, and focusing closer makes it much shallower. Sensor size matters because a smaller sensor needs a shorter lens for the same framing, which is why phones keep almost everything sharp.
The calculator uses the standard thin-lens formulas. Hyperfocal distance H = f² ÷ (N × c) + f. Near limit = s(H − f) ÷ (H + s − 2f), and far limit = s(H − f) ÷ (H − s), which becomes infinity once you focus at or beyond H. Depth of field is usually split about one third in front of the subject and two thirds behind, but at close distances it becomes nearly even.
Hyperfocal focusing for landscapes
When you focus at the hyperfocal distance, everything from half that distance to infinity is acceptably sharp. With a 24 mm lens at f/11 on full frame, H is about 1.8 m, so focusing there keeps everything from 0.9 m to the horizon sharp. Use it for landscapes and street photography where you want maximum depth without focus stacking.
What circle of confusion should I use?
0.030 mm is the common standard for full frame, based on a print viewed at a normal distance. If you print large or check images at 100% on a high-resolution sensor, use a smaller value such as 0.020 mm for a stricter result.
Why is my background still blurry at f/8?
With long lenses and close subjects, depth of field can be only centimetres even at f/8. Check the far limit: anything beyond it is outside the sharp zone.
Is depth of field the same as background blur?
Not exactly. Depth of field tells you what looks sharp. How blurry the background looks depends on how far beyond the far limit it is, and on the lens.
Should I enter the focal length printed on my phone?
Use the real focal length (for example 6.9 mm), not the 35 mm equivalent (24 mm), together with the Phone sensor option.