Optical centre: The visual centre o fa page.

视觉中点：页面视觉上的中心点。

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Focal length is the distance between optical centre and principal focus.

焦距就是镜片中心和焦点之间的距离。

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Widely applied for repair centre (circuit board and component) jewelry shop (silver) optical shop (glasses) watch shop (metal bracelet) beauty shop (scissors clip) and home user (denture) etc.

适用于维修中心(电路板及电子组件)，首饰店(银器)，钟表店(金属表带)，眼镜店(眼镜)，美容店(剪刀及夹子)，家用(假牙)等等。

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Widely applied for repair centre (circuit board and component) jewelry shop (silver) optical shop (glasses) watch shop (metal bracelet) beauty shop (scissors clip) and home user (denture) etc.

适用于维修中心(电路板及电子组件)，首饰店(银器)，钟表店(金属表带)，眼镜店(眼镜)，美容店(剪刀及夹子)，家用(假牙)等等。

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