A Complete Breakdown of Aperture Stops & Light Intake Multipliers-Knowledge Encyclopedia-Shenzhen Kai Mo Rui Electronic Technology Co. LTD

A Complete Breakdown of Aperture Stops & Light Intake Multipliers

Source：Shenzhen Kai Mo Rui Electronic Technology Co. LTD2026-06-16

The multiplier relationship of aperture fundamentally refers to the multiplicative ratio of light intake. Unlike shutter speed, this relationship is not intuitive, as it lies behind the seemingly confusing f-number values. Mastering this logic lets you fully grasp exposure calculations.

01 Core Rule: Link Between f-stop Multiples and Light Volume

First, memorize the standard full-stop aperture sequence:

f/1.4 → f/2 → f/2.8 → f/4 → f/5.6 → f/8 → f/11 → f/16 → f/22

Key Takeaway: Light intake doubles or halves between two adjacent full stops (e.g., from f/2.8 to f/4).

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When the f-number increases by one stop (e.g., f/2.8 → f/4): Light intake is cut in half.
When the f-number decreases by one stop (e.g., f/4 → f/2.8): Light intake doubles.

02 The Mathematical Principle Behind the Rule

To understand this rule, we first clarify how f-numbers are defined:

f-number = Lens focal length ÷ Diameter of the aperture iris opening

Example: A 50mm lens with a 25mm-wide aperture iris produces an f-stop of 50 ÷ 25 = f/2.

Critical point: Light intake depends on the area of the aperture opening, not its diameter.

The aperture iris is a circle, with area calculated as: A=πr2 (r = radius).

To double the amount of light entering the lens, the iris area must double.

Mathematically, doubling a circle’s area requires its diameter (or radius) to multiply by 2 (≈1.414).

This is why the full-stop aperture sequence forms a geometric progression with a common ratio of √2 ≈ 1.414:

1 → 1.4 → 2 → 2.8 → 4 → 5.6 → 8 → 11 → 16 → 22 ...

(1.4 ≈ √2, 2 ≈ 1.4×1.4, 2.8 ≈ 2×1.4, and so on)

Author’s note: You don’t need to fully memorize this math; just grasp the general logic behind the sequence.

03 Practical Guide: Adjust Exposure to Compensate for Aperture Shifts

The table below illustrates how to offset one stop of aperture change to maintain consistent exposure.

Example Scenario

Baseline exposure settings: ISO 100, f/8, 1/125s

Suppose you want a deeper depth of field and stop down the aperture one full stop to f/11 (light intake halved). To retain correct exposure, choose one compensation method:

Slow the shutter speed one stop to 1/60s (doubles exposure time to recover lost light)
Raise ISO one stop to ISO 200 (doubles sensor light sensitivity)

Valid equivalent exposure combinations:

ISO 100, f/11, 1/60s | ISO 200, f/11, 1/125s