### Princeton's WordNet

focal ratio, f number, stop number, speed(noun)

the ratio of the focal length to the diameter of a (camera) lens system

### ChatGPT

focal ratio

The focal ratio, also known as f-number, f-stop, or relative aperture, is a dimensionless number that quantifies the ratio of the focal length of a lens to the diameter of the entrance pupil or aperture. It is a measure of lens speed, describing the brightness of the image that will be formed for a given exposure time. A smaller f-number denotes a larger aperture, which allows more light to reach the image sensor, ideal for low-light conditions. Conversely, a larger f-number denotes a smaller aperture, providing a wider depth of field.

### Matched Categories

### Numerology

Chaldean Numerology

The numerical value of focal ratio in Chaldean Numerology is:

**1**Pythagorean Numerology

The numerical value of focal ratio in Pythagorean Numerology is:

**1**

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