Point the camera at a white background, and observe this phenomenon with a magnifying glass.

将相机对准白色背景，然后用放大镜观察这种现象。

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The opacity can depend on the distance to the camera, meaning that the images in the background can be a little transparent to give the feeling of depth.

不透明度可以根据离摄像机的远近来确定，也就说，背景中的图形要更加不透明一些，给人以纵深感。

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Basically, it is the ability to use your camera and lenses to control the relationship between the background and foreground of your pictures.

基本上讲，就是用你的相机和镜头去控制照片中背景和前景关系的能力。

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Plenty of measures can tell you something about the user's state of mind: keystrokes, how many windows are open and their content, whether the user is scrolling, the time of day, the contents of a desktop calendar even background noises from a microphone and visual information from a camera.

ECONOMIST: Computing

In her white-washed office set against a pulsating Times Square background, Wintour sat sipping a lipstick-stained Starbucks and sneaking emails before the camera was on.

FORBES: Vogue's Anna Wintour: Intimidating, No. Powerful, Yes.

The lens' wide F2 maximum, 9-bladed circular aperture enable beautiful background defocus ('bokeh') effects to rival or exceed professional-class DSLR camera lenses.

ENGADGET: Sony's Cyber-shot RX1 compact camera packs a full-frame sensor, 'fits in your palm' (hands-on)