英语 ⇄ 俄语 德语 +

image-side focal length
光学	bildseitige Brennweite (distance from the centre of a lens to its principal focus on the image side); hintere Brennweite (distance from the centre of a lens to its principal focus on the image side)
image side focal length
光学	Bildbrennweite f (distance from the centre of a lens to its principal focus on the image side)