Physics
Diopter Calculator
Convert focal length to lens power in diopters.
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Lens power in diopters is the reciprocal of the focal length in metres.
The math behind it
P = 1/f. A 0.5 m focal length is +2 D; shorter focal lengths give stronger lenses.
Worked Example
f = 0.5 m → +2 diopters.
Frequently Asked Questions
What does a negative diopter mean?
A diverging (concave) lens, used to correct nearsightedness.
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