About & credits
Depth of Field is an educational simulator. It shows how focal length, aperture, framing and subject distance shape the zone of acceptable sharpness, so photographers can make informed choices about equipment and settings before taking a picture.
The formulas (FR-CALC-06)
With focal length f (mm), f-number N, circle of confusion c (mm) and subject distance s (converted to mm):
- Hyperfocal distance
- H = f² / (N · c) + f
- Hyperfocal distance is the closest distance at which a camera lens can be focused while keeping objects at infinity acceptably sharp. When you focus your lens at this specific distance, the Depth of Field extends from half of that hyperfocal distance all the way to infinity.
- Near limit
- Dₙ = s · (H − f) / (H + s − 2f)
- Far limit
- D𝒇 = s · (H − f) / (H − s)
- Depth of field
- DoF = D𝒇 − Dₙ
If s ≥ H, the far limit is at infinity and the depth of field is infinite. The blur shown in the simulated photograph is derived from the physical blur-disc diameter b(x) = f² / (N·(s−f)) · |x−s| / x, scaled to the rendered image width.
The circle of confusion is a property of the sensor format: for full-frame (36 × 24 mm) it is 0.030 mm.
Image credits (AC-13)
Every bundled background and subject image carries a free licence. Licence, source and author are listed here and stored with the image.
Backgrounds
Subjects
Limitations
Approximation for educational purposes — not a photometric rendering. Optical aberrations, focus breathing and aperture-blade shape are not modelled. Release 1 covers the full-frame (36 × 24 mm) format only.