At present, some difficulties are encountered in measurement of long focal length of lens.

目前，透镜长焦距的有效测量还存在一些难题。

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A new method of measuring the monochrome focal length of lens is given from the single slit diffraction principle.

根据单狭缝衍射原理，提出了一种测量透镜单色焦距的新方法。

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Linear CCD is used as receiver on behalf of eyes on the basis of originally experimental equipment measuring the focal length of lens.

在原来光具座测量透镜焦距的装置基础上，用CCD代替人眼作接收器时，正确判定焦面是实验的关键。

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By using this adapter to attach any K-mount lens onto a PENTAX Q series camera, the focal length of the lens is extended by approximately 5.5 times in the 35mm format.

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With three glass lens elements in three groups, it can be used as a wide-angle lens equivalent with a single focal length of 30mm (35mm camera equivalent).

ENGADGET: Olympus E-PL5 and E-PM2: Micro Four Thirds cameras with OM-D-like focusing, performance boosts (hands-on)

Mastcam-34 has a 34mm lens, or a 35mm-equivalent focal length of 115mm.

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