Not round and on one side it will be elongated vertical and the other side horizontal then as you go more defocus it will snap to a perfect symmetrical circle.

如果在一面是垂直拉伸的，在另一面水平方向，如果你继续散焦，会变成对称的圆环。

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The outer circle of the vertical pole is provided with a guiding elongated slot, and the slot base of the guiding elongated slot is processed with two small grooves which are respectively arranged.

立柱的外圆上设有一导 向长槽，在导向长槽的槽底加工有二个分别设置的小凹槽。

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