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.

當您在某些自動模式(如程序)或半手動模式(如光圈優先或快門速度優先)之一中使用相機時，您不會放棄對一切的完全控制：您仍然可以使用曝光補償來控制曝光。 這是這樣的。

相機的測光表所見 (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.

當您的相機計算出要使用的曝光設置時，會做出一個大的假設：將所有內容平均后，它前面的顏色幾乎是灰色的。 換句話說，所有的明暗平衡都達到了中間的灰色。

This is the photo your camera is trying to take.

這是您的相機試圖拍攝的照片。

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

而且，這是一個很好的近似值。 這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.

這不是一個完美的匹配，但是您的相機(假設正在嘗試拍攝無聊的灰色墻壁的照片)將在很多場景中處于正確的位置。

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

但是，并非每個場景都適用。 這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.

這次，所有場景都比中間灰色要亮一些。 發生這種情況時，如果您將相機保持在自動模式，則會使照片曝光不足，因此您會得到像右側圖像而不是左側圖像正確曝光的圖像。

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.

這并不理想，因為您將在那些深黑色陰影中丟失大量圖像數據。 這就是曝光補償的來源。

使用曝光補償 (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.

曝光補償是一種讓相機改變測光表建議的曝光的方法，如果您認為它不會給您想要的結果。 如果場景比中間的灰色明亮，則需要使圖像過度曝光。 如果較暗，則必須使鏡頭曝光不足。

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.

像曝光有關的所有事情一樣，曝光補償以檔為單位進行測量。 一個光圈代表入射到傳感器的光量增加了一倍，盡管這并不一定意味著您的照片將顯示兩倍的亮度。

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.

大多數相機在光圈優先，快門速度優先和程序模式下都可以使用曝光補償。 您也可以在全自動模式下使用它，但不能保證。

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

當您通過取景器或背面屏幕查看時，您會看到曝光補償圖。

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是沒有補償的場景的測量值。 -1，-2和-3是曝光不足的一個，兩個或三個光圈，而+ 1，+ 2和+3是曝光過度的一個，兩個或三個光圈。 要調整曝光補償，通常會按住曝光補償按鈕(即上圖中的半黑色半白色正方形)并轉動主設置撥盤，盡管此過程可能因相機而異。 如果不確定，請查閱手冊。

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

在上圖中，我現在停止曝光不足。 這是實際中不同補償值的樣子。

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.

如果情況真的好起來，一次曝光不足即可。 如果情況真的很暗，請停止曝光過度。 一到兩檔曝光補償通常足以適應任何場景。 我不確定我是否曾經使用過正負三項的曝光補償。

翻譯自: https://www.howtogeek.com/398464/what-is-exposure-compensation-in-photography/