| Webster's Online Dictionary |
| Expressions | Domain | Definition | |
| Equivalent focal length | Business | The focal length of a group of lenses considered as a single lens. (references) | |
| Equivalent focal length | Environment | The distance measured along the lens axis from the rear nodal point to the plane of best average definition over the entire field used in the aerial camera. (references) | |
Source: compiled by the editor from various references; see credits. | Top | ||
