摄影中的曝光补偿是什么？

When you use your camera in some automatic modes like Program—or one of the semi-manual modes like Aperture Priority or Shutter Speed Priority—you don’t give up total control over everything: you can still control the exposure using exposure compensation. Here’s how that works.

当您在某些自动模式(如程序)或半手动模式(如光圈优先或快门速度优先)之一中使用相机时，您不会放弃对一切的完全控制：您仍然可以使用曝光补偿来控制曝光。这是这样的。

相机的测光表所见 (What Your Camera’s Light Meter Sees)

When your camera calculates what exposure settings to use, it makes one big assumption: that when you average everything out, what’s in front of it is pretty much gray. In other words, all the lights and darks sort of balance out to a middle gray.

当您的相机计算出要使用的曝光设置时，会做出一个大的假设：将所有内容平均后，它前面的颜色几乎是灰色的。换句话说，所有的明暗平衡都达到了中间的灰色。

This is the photo your camera is trying to take.

这是您的相机试图拍摄的照片。

And, it’s a pretty good approximation. Here are some of my photos with the luminosity levels averaged out.

而且，这是一个很好的近似值。这是我的一些平均亮度水平的照片。

It’s not a perfect match, but your camera, just by assuming it’s trying to take a photo of a boring gray wall, is going to be in the right ballpark for a lot of scenes.

这不是一个完美的匹配，但是您的相机(假设正在尝试拍摄无聊的灰色墙壁的照片)将在很多场景中处于正确的位置。

But not for every scene. Here are some more photos of mine averaged out.

但是，并非每个场景都适用。这是我的一些平均照片。

This time, all the scenes are a good bit brighter than middle gray. When this happens, if you leave your camera in automatic mode, it’s going to underexpose the shots, so you’ll get something like the image on the right rather than the one on the left, which is correctly exposed.

这次，所有场景都比中间灰色要亮一些。发生这种情况时，如果您将相机保持在自动模式，则会使照片曝光不足，因此您会得到像右侧图像而不是左侧图像正确曝光的图像。

Not ideal since you’re going to lose a considerable amount of image data in those dark black shadows. This is where exposure compensation comes in.

这并不理想，因为您将在那些深黑色阴影中丢失大量图像数据。这就是曝光补偿的来源。

使用曝光补偿 (Using Exposure Compensation)

Exposure compensation is a way of getting your camera to alter the exposure the light meter is suggesting if you don’t think it will give you the results you want. If the scene is brighter than middle gray, you need to overexpose the image a bit. If it’s darker, you have to underexpose the shot.

曝光补偿是一种让相机改变测光表建议的曝光的方法，如果您认为它不会给您想要的结果。如果场景比中间的灰色明亮，则需要使图像过度曝光。如果较暗，则必须使镜头曝光不足。

Like everything to do with exposure, exposure compensation is measured in stops. A single stop represents a doubling of the amount of light hitting the sensor—although that doesn’t necessarily mean that your photo will appear twice as bright.

像曝光有关的所有事情一样，曝光补偿以档为单位进行测量。一个光圈代表入射到传感器的光量增加了一倍，尽管这并不一定意味着您的照片将显示两倍的亮度。

Exposure compensation is available in Aperture Priority, Shutter Speed Priority, and Program modes on most cameras. You may also be able to use it in fully automatic mode, but it’s not guaranteed.

大多数相机在光圈优先，快门速度优先和程序模式下都可以使用曝光补偿。您也可以在全自动模式下使用它，但不能保证。

When you look through the viewfinder or on the back screen, you’ll see an exposure compensation graph.

当您通过取景器或背面屏幕查看时，您会看到曝光补偿图。

0 is the metered value of the scene with no compensation. -1, -2, and -3 are one, two, or three stops underexposed while +1, +2, and +3 are one, two, or three stops overexposed. To adjust the exposure compensation, you normally hold the exposure compensation button—it’s the half-black half-white square in the image above—and turn the primary settings dial, although the process can vary between cameras. Check the manual if you’re unsure.

0是没有补偿的场景的测量值。 -1，-2和-3是曝光不足的一个，两个或三个光圈，而+ 1，+ 2和+3是曝光过度的一个，两个或三个光圈。要调整曝光补偿，通常会按住曝光补偿按钮(即上图中的半黑色半白色正方形)并转动主设置拨盘，尽管此过程可能因相机而异。如果不确定，请查阅手册。

In the image above, I’m now underexposing by a stop. Here’s what the different compensation values look like in practice.

在上图中，我现在停止曝光不足。这是实际中不同补偿值的样子。

If things are really bright out, underexpose by a single stop; if things are really dark, overexpose by a stop. A stop or two of exposure compensation is normally more than enough to adapt for any scene. I’m not sure I’ve ever had to use exposure compensation of plus-or-minus three.

如果情况真的好起来，一次曝光不足即可。如果情况真的很暗，请停止曝光过度。一到两档曝光补偿通常足以适应任何场景。我不确定我是否曾经使用过正负三项的曝光补偿。