PHYSICAL QUANTITY

Focal length: formulas and units of measurement

Focal length: symbol F, unit m. Formulas and explanations for Optics.

FF\text{м}meter

KEY CONNECTIONS

Formulas

\frac{1}{F}=\frac{1}{d}+\frac{1}{f}1 / F = 1 / d + 1 / f

F=\frac{df}{d+f}F = df / (d + f)

D=\frac{1}{F}D = 1 / F

NOTATION

F: Focal length is the distance from the optical center of the lens to its main focus.
d: Object distance - the distance from the lens to the object in question.
f: Image distance is the distance from the lens to the resulting image.
D: Optical power is the ability of a lens to collect or scatter light.

THEORY

PRACTICE