p光圈和dc光圈的区别

In photography, the aperture is the hole in a lens that lets light into your camera.

在摄影中，光圈是镜头上的Kong，可让光线进入相机。

When you take a photo, the shutter inside your camera swings up and lets light hit the sensor. How much light hits the sensor is determined by two things: how long the shutter is open for and how big a hole—the aperture—the light has to get through. The more light that hits the sensor, the brighter the image. We’ve already looked at shutter speed, so let’s explore the aperture.

拍照时，相机内部的快门会向上摆动，让光线照射到传感器上。 多少光照射在传感器上取决于两件事：百叶窗打开多长时间以及光必须通过多少个Kong(光圈)。 照射到传感器的光越多，图像就越亮。 我们已经研究了快门速度 ，因此让我们探索光圈。

光圈如何运作 (How Aperture Works)

Imagine trying to fill a bucket of water in a rainstorm. The aperture is the size of the hole at the top of the bucket. If you’ve got three different buckets, each with the same capacity but a different sized hole, then the one with the biggest hole will fill up fastest. This is the same as what happens when you take a photo.

想象一下在一场暴雨中试图装满一桶水。 Kong径是铲斗顶部Kong的大小。 如果您有三个不同的铲斗，每个铲斗具有相同的容量，但Kong的大小不同，那么装满最大Kong的铲斗将最快装满。 这与拍摄照片时的情况相同。

If the aperture is really big, loads of light pours through, and you don’t have to hold the proverbial bucket out in the rain for long (which means you can use a faster shutter speed). If the aperture is really small, a lot less light squeezes in, so you’re stuck standing around in the rain for a lot longer.

如果光圈确实很大，则大量的光会直射，而不必在雨中长时间撑起众所周知的水桶(这意味着您可以使用更快的快门速度)。 如果光圈确实很小，则挤入的光要少得多，因此您会在雨中停留更长的时间。

So why then, don’t we always use a really big aperture? Because the aperture also affects other parts of the image, too. When rain falls into the bucket through a really big hole, it’s splashing in from all directions. Some of the rain drops will be blown in by the wind, some might be dripping off a tree, and so on. When rain falls into a bucket through a really narrow hole, it can only come in from one angle: if it’s blown around by the wind, it’s going to miss the bucket or hit the edge.

那么，为什么不总是使用一个很大的光圈呢？ 因为光圈也会影响图像的其他部分。 当雨水从一个大洞掉进水桶时，雨水从四面八方飞溅。 一些雨滴会被风吹走，有些可能会从树上滴下来，依此类推。 当雨水通过一个非常狭窄的Kong落入水桶时，只能从一个角度进来：如果被风吹走，它将错过水桶或撞到边缘。

The same is true for light: with a really big aperture, a lot of light gets let in, but it comes in from different directions—in physics speak, it’s uncollimated. With a really narrow aperture, only light that comes in at a very specific angle gets through the hole so all the light is coming from the exact same direction—it’s collimated. The collimation of the light determines the depth of field of your photo. And this is the crux of it.

光线也是如此：具有很大的光圈，可以让很多光线进入，但光线来自不同的方向-从物理学的角度来说，它是无准直的 。 Kong径非常狭窄，只有以特定角度入射的光线才能通过Kong，因此所有光线都来自完全相同的方向，即经过准直。 光线的准直度决定了照片的景深 。 而这就是症结所在。

Look at the photo above. Only the model is in focus. Everything else behind her is blurry. This means it has a really shallow depth of field. The area that’s sharp is tiny. I took this photo with a wide aperture so light poured in from all directions. A lot of it wasn’t focused properly when it hit the sensor; only the light bouncing directly off the model was coming in at the right angle.

看上面的照片。 仅关注模型。 她身后的其他一切都很模糊。 这意味着它的景深非常浅。 尖锐的区域很小。 我以较大的光圈拍摄了这张照片，所以光线从各个方向射入。 当它撞到传感器时，很多都无法正确聚焦； 只有直接从模型反射的光才以正确的角度入射。

Now, in this photo, everything is sharp and in focus. It’s got a really big depth of field. This is because I used a narrow aperture. Even though light was coming from all sorts of different directions, only light from a specific angle was able to get through the small hole. Since all the light is coming in from the same direction, it hits the sensor in the same way: perfectly in focus.

现在，在这张照片中，一切都变得清晰而清晰。 它的景深非常大。 这是因为我使用了狭窄的光圈。 即使光线来自各种不同的方向，也只有特定角度的光线才能通过小Kong。 由于所有的光都来自同一方向，因此它以相同的方式入射到传感器上：聚焦完美。

光圈如何测量 (How Aperture is Measured)

Shutter speed is simple to measure: it’s done in seconds or fractions of a second. Aperture is a little harder to measure because the size of the hole is only one part of the equation: what matters is how big the hole is relative to the focal length of the lens.

快门速度易于测量：只需几秒钟或几分之一秒即可完成。 Kong径很难测量，因为Kong的大小只是方程式的一部分：重要的是Kong相对于镜头焦距的大小 。

Think of it this way: if you’ve got a meter-high bucket and the hole at the top is 10 centimeters wide, then that’s a pretty narrow aperture (at least relative to our bucket). On the other hand, if you’ve got a bucket that’s 10 centimeters high with a 10 centimeter wide hole, then that’s (again, relative to our bucket) a pretty wide aperture. Knowing that the hole is 10 centimeters wide doesn’t tell us very much on its own.

这样想：如果您有一个米高的水桶，而顶部的Kong是10厘米宽，那么这是一个相当狭窄的Kong径(至少相对于我们的水桶而言)。 另一方面，如果您有一个高10厘米，宽10厘米的Kong的水桶，那么(同样，相对于我们的水桶)，这是一个相当宽的Kong径。 知道这个Kong是10厘米宽，并不能告诉我们很多。

Aperture, then, is measured in f-stops. This is just the ratio between the focal length, how tall the bucket is, and the aperture. Most lenses you can buy have a range of f-stops between about f/1.8 and f/22. This means the ratio of the focal length (f) to the aperture is between 1.8 and 22.

然后， 以光圈为单位测量光圈。 这只是焦距，桶的高度和光圈之间的比率。 您可以购买的大多数镜头的光圈值范围介于f / 1.8和f / 22之间。 这意味着焦距(f)与光圈的比率在1.8到22之间。

If you do the math, it’s easy to see that a low f-number is a wider aperture. For example, if you use a lens with a 100mm focal length, then at f/1.8 the aperture is about 55mm wide (100/1.8). On the other hand, at f/22 the aperture is about 4.55mm wide (100/22).

如果进行数学计算，很容易看到低f值表示较宽的光圈。 例如，如果使用焦距为100mm的镜头，则在f / 1.8时，光圈约为55mm宽(100 / 1.8)。 另一方面，在f / 22时，Kong径约为4.55mm宽(100/22)。

With aperture, we don’t actually need to know exactly how many millimeters wide the hole is. All that matters is the f-number. That’s because, thanks to some fairly complex math, the ratio of the aperture to the focal length has consistent properties regardless of what the focal length of the lens actually is. An aperture of f/1.8 acts the same whether you’re using a 100mm lens or a 1000mm lens.

有了光圈，我们实际上并不需要确切知道Kong的宽度是多少毫米。 重要的是f数。 这是因为，由于一些相当复杂的数学运算，无论镜头的焦距是多少，光圈与焦距的比率都具有一致的属性。 无论您使用100mm镜头还是1000mm镜头，f / 1.8的光圈都具有相同的作用。

您应该使用什么光圈？ (What Aperture Should You Use?)

Aperture is incredibly important in photography. If you want to take good photos, you need to know how to choose the right aperture. It’s also important to understand how it interacts with the two other important camera settings: shutter speed and ISO. Check out our guide to shutter speed, aperture and ISO for everything you need to know.

光圈在摄影中非常重要。 如果要拍摄优质照片，则需要知道如何选择合适的光圈。 了解它如何与其他两个重要的相机设置进行交互也很重要：快门速度和ISO。 查看我们有关快门速度，光圈和ISO的指南，以了解您需要了解的所有内容。

Image Credits: Cbuckley/Wikimedia.

图片来源： Cbuckley / Wikimedia。

翻译自: https://www.howtogeek.com/299965/what-is-aperture/

p光圈和dc光圈的区别