Spanish Distancia focal Cited by user Uruk on 11 Dec 2022 La distancia focal o longitud focal de un lente es la distancia entre el centro óptico de la lente y el foco (o punto focal).
English Focal length Cited by user InternetArchiveBot on 28 Jan 2020 The focal length of an optical system is a measure of how strongly the system converges or diverges light; it is the inverse of the system's optical power.
English Cold camera photography Cited by user Dawnseeker2000 on 12 Apr 2019 Cold Camera Photography is a technique used by astrophotographers to avoid noise when taking shots with very long exposures using DSLRs or traditional film cameras.