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- second focal length 第二焦距
- A typical lens has a focal length(f)of 625 mm. 常见镜头的焦距（f）为625毫米。
- Determine the focal length of your lens. 决定你镜头的焦距。
- C: Can I control the focal length? 我能控制焦距吗?
- What is the best focal length for bird photography? 拍摄鸟儿最适合的焦距长度是多少?
- The second property concerns the brightness of a projected image, which depends on the focal length and facial, or surface, area of the imaging mirror. 第二项考虑的特性是投影的明亮度，这要视焦距与镜面（镜子的表面）而定。
- The focal length of a given lens is different for different colors. 一个特定的透镜的焦距因颜色的不同而不同。
- The focal length is set to Flat stitch in the Properties window. 焦距在特性窗囗中被设定成平坦的一针。
- My finding about the unlikely focal length of the putative projection mirror has a second implication, even more constraining to the Hockney theory. 既然设想中投射镜的焦距不太可能实现，我的发现还延伸出第二个推论，更使霍克尼的理论受限。
- This photogragh is shot by lens with a long focal length. 这张照片是用长镜头拍摄的。
- The focal length of the camera lens plays an important role in photo criteria. 摄影机镜头的焦距在摄影规范中起着重要的作用。
- Focal length The distance between the centre of a lens and its principal focus. 镜头中心与其主焦点的距离。
- The solid tunable focal length microlens in our study is still a prototype. 本研究所提出之固态调焦透镜兼具微小化、积体化、可单一或阵列使用、及系统整合性高等优点。
- Here the combinations of Testcharts and measuring objectives for different focal length ranges are preset. 在这里预置不同焦距范围的测量物镜与测试图表之间的组合。
- Spot diameters of just a few thousands of an inch can readily be attained with convenient short focal length lenses. 用普通的短焦距透镜不难得到直径只有几十微米的光点。
- The focal length of the conelensing lens should be such that the image of the source just fills the projecting lens. 聚光透镜的焦距应使光源的像正好照满放映透镜。
- As a result, the focal lengths in these planes will be different. 结果，这两个平面内的焦距将不同。
- A unit of measurement of the refractive power of lenses equal to the reciprocal of the focal length measured in meters. 屈光度透镜或棱镜折光率的一种量度，等于以米计算焦距之倒数
- In taking a picture, the shutter,the focal length and the other things must be adjusted as the case may be. 在拍照过程中，快门、焦距等等必须按实际情况加以调整。
- In order to be able to evaluate a large focal length range, different converter lenses must be used. 为了能够计算较大的焦距范围,根据焦距的大小必须使用不同的转换透镜。
