| Webster's Online Dictionary |
| Expressions | Domain | Definition | |
| Effective focal length | Electrical Engineering | The distance between the center plane of the front lens and the plane of the focal spot. Source: European Union. (references) | |
| Effective focal length (USGS) | Environment | The adjusted value of the focal length of a lens which best fulfills the geometric conditions of a given photogrammetric operation. In making diapositive plates, the settings of the printer are based on the effective focal length derived from the calibrated focal length and further adjusted to allow for film distortion. In photoalidade operation, the effective focal length is the setting of the focal-length scale which best brings a specific photograph into proper geometric perspective. The preferred expression for this value is “ principal distance.”. (references) | |
Source: compiled by the editor from various references; see credits. | Top | ||
