black card

基本解释

A black card is just a regular cardboard paper. The key point is the color black. Black absorbs light. Therefore, the camera will not capture the black card.
黑卡，就是一般的纸，重点是要黑色，黑色会吸光，如此相机才不会拍摄出这片卡的颜色。
Try the technique before you buy with a DIY alternative. Roll a sheet of black card into a cone and place a strip of black or gaffer tape along the seam to hold it securely in place.
在买之前先自己DIY一个，把一张卡纸卷成圆锥型，用电工黑胶粘牢。
If you don't shake the black card, it will leave a very clear line on your photo.
若不晃动黑卡，影像中会留下一条很明显的直线。

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