f-number (P5858)
ratio of the system's focal length to the diameter of the entrance pupil. Sample: 4 (generally written "ƒ/4") for a lens with 200 mm focal length using an entrance pupil diameter of 50 mm.
- focal ratio
- ƒ-number
- f-ratio
| Language | Label | Description | Also known as |
|---|---|---|---|
| English | f-number |
ratio of the system's focal length to the diameter of the entrance pupil. Sample: 4 (generally written "ƒ/4") for a lens with 200 mm focal length using an entrance pupil diameter of 50 mm. |
|
Data type
Quantity