22C-D022N103

22C-D022N103

22C-D022N103

22C-D022N103

这里关键要了解的是这个分数：如果你用一支焦距为50mm的镜头拍摄，光圈为f/2.0，这就意味着开孔的直径是25mm（译注：应该是入瞳直径为25mm，并非光圈的物理直径）。怎么得到的？50/2=25。类似的，如果你用f/4.0光圈拍摄，孔径就是50/4=12.5mm。

你是否已经注意到，当f值变大时，光圈会变小？这一点很重要。f值是分数，所以f/2比f/4大，f/4又比f/8大。

光圈如何影响镜头？

你可能已经想到了，较大的光圈（较小的f值）意味着有更多光线通过镜头，这有助于在弱光环境中拍摄。

在选择镜头时，要考虑的重要的一点就是大光圈。大光圈可以表示一支镜头有多“亮”。一般来说，越亮越好。

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