We investigate the dependence of the focusing contribution on the order m of local ring of underlying traditional Fresnel zone plate.

在本文中，我们讨论了聚焦贡献对潜在的传统菲涅耳波带片上的环的阶次的依赖性。

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With the structure, the focusing ring can be quickly clamped on the optical mode lens; and assembly and disassembly are convenient and positioning is accurate.

由于本实用新型采用了上述结构，调焦环可快速地卡装在光模镜头上，拆装方便、定位准确。

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The second version also has wider and deeper knurling on the focusing ring than the previous version.

第二版调焦环上的棱比前一版更宽更深。

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It is possible to use the focus ring for focusing just like an SLR camera.

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Additionally, it features a macro switching ring on the lens barrel which instantly shortens the minimum focusing distance to approximately 20cm (from image plane), allowing the camera to capture small, close-up subjects with exquisite detail.

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In macro mode, which can be set by pushing the zoom ring forward while depressing the macro button on the side of the lens, focusing is possible between 8 and 20 inches for close-up shooting with a maximum image magnification of 0.72X (35mm camera equivalent).

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