Kostenloser Focal Length Rechner
Berechnen Sie focal length aus object und image distances. Kostenloser focal length und diopter Rechner.
Brennweite
10.00 cm
Focal Length vs Object Distance
Formel
Focal Length
The focal length defines the converging or diverging power of a lens or mirror.
Formula
1/f = 1/d_o + 1/d_i
Lens power in diopters is D = 1/f (with f in meters). Positive focal length = converging lens; negative = diverging.
Lösungsbeispiel
An object at 30 cm produces an image at 15 cm.
- 011/f = 1/do + 1/di
- 021/f = 1/30 + 1/15
- 031/f = 0.0333 + 0.0667 = 0.1
- 04f = 10 cm
- 05Power = 100/10 = 10 diopters
Häufig Gestellte Fragen
What are diopters?
The unit of lens power, equal to 1/f where f is in meters. Eyeglass prescriptions use diopters. Positive = farsighted correction; negative = nearsighted.
How does focal length relate to camera zoom?
Longer focal length gives higher magnification and a narrower field of view (telephoto). Shorter focal length gives a wider field of view (wide-angle).
What determines the focal length of a lens?
The curvature of the lens surfaces and the refractive index of the glass. The lensmaker's equation relates these to focal length.
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