Focal

(adj.) having or localized centrally at a focus; 'focal point'; 'focal infection' .

(adj.) of or relating to a focus; 'focal length' .

以斯拉录入

• The more curved the lens, the shorter the focal length, and the nearer the focus is to the lens. 伯莎M.克拉克. 科学通论.
• He made use of telescopes 20 and 40 feet in focal length, and of 18. 李贝. 西洋科学史.
• The distance of the principal focus from the lens is called the focal length of the lens, and from the diagrams we see that the more convex the lens, the shorter the focal length. 伯莎M.克拉克. 科学通论.

校对:赛克