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  • 0-9

Aperture, Aperture Value

The amount of light passing through the lens is controlled by the aperture hole. The aperture value indicates how much light can pass through.

Since it is expressed as f/2.8, f/16, etc., it is also called the "f-number." The f/1 aperture value represents the maximum diameter of the aperture. When the aperture is half the size, it is called f/2, and when a quarter of the full size, it is f/4.

The f-number is therefore the denominator of the fractional size. The larger the denominator or f-number, the smaller the aperture size and the less light can pass through. Note that although f/2 is half the diameter of f/1, the total area of the hole is only one-fourth of the full-size hole (1/2 x 1/2 = 1/4). And so the amount of light passing through is only 1/4 that of the full-size hole.

When the f-number is doubled, the amount of light shrinks to 1/4 of amount.