A range in relation to an optical system, such as a camera lens, representing distances great enough that light rays reflected from objects within the range may be regarded as parallel. (聚焦區)無限遠與光學系統(如照像鏡頭)有關的一個範圍,表示距離是如此之遠,以至於從在這一距離的物體上反射回來的光可以視為平行光線