根据您提供的信息，我为您撰写了一篇关于单反相机测光模式选择的新闻稿。以下是新闻稿的内容：
单反相机测光模式选择：取景器、屏幕拍照两者不一样
在相机界面会看到一个测光选项，里面包含了多种测光模式，如点测光、平均测光、矩阵测光等等。什么叫测光，测光的工作原理和用途是什么呢？这一点想必很多人都知道。但是单反相机用户需要注意，使用相机上方的取景器拍照，与使用电子屏幕拍照，两者的测光设定有区别。
01、什么叫测光
光圈、快门、感光度三者相互配合，控制着照片的亮度。光圈大了，亮度就高。快门时间长了，亮度就高。iso 高了，照片就亮。外界环境的亮度不断变化，正午就比早晨亮，晴天就比阴天亮，对吧？相机打开后，会一直“测”外界“光”的亮度，从而给出一个光圈-快门-感光度搭配数值，保证拍到的照片亮度正常。当用 M 档（手动模式）拍照时，测光就没用了，因为此时光圈、快门、感光度无法自动调整。只有相机至少能自动调节其中 1 项的时候，测光工作才有意义。
02、测光模式选择
不同的测光模式，实则是在更改测光区域。有测整个画面的，有测一小部分画面的，还有测一个点的，也有把中间和四周分开测然后中间占大头儿的。相机只保证测的区域亮度正常，其它地方我不管。举个例子，你拍摄日落的时候，太阳在画面中只占很小的一部分。如果只测太阳，那太阳的亮度就是正常的。如果你测全局，大部分环境都比较暗，相机就会提亮曝光，太阳也就过曝了。各厂家的名字不一样，原理都是一样的。以佳能相机为例，名字分别是评价测光、局部测光、中央重点测光、点测光。其他厂家还有平均测光、矩阵测光等命名方式。详情看这篇文章：相机 4 种测光模式怎么选？教你正确使用测光功能！
英语如下：
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“News Headline: Choosing the Exposure Mode in Single-lens Re====
“News Headline: Choosing the Exposure Mode in Single-lens Reflex Cameras: A Big Difference Between Viewfinder and Screen Photography
Keywords: Single-lens Reflex Camera, Exposure Mode, Viewfinder and Screen
News Content: Based on the information you provided, I have written a news article about choosing the exposure mode in single-lens reflex cameras. Here is the content of the news article:
Single-lens Reflex Camera Exposure Mode Selection: A Big Difference Between Viewfinder and Screen Photography
In the camera interface, you will see an exposure option that contains various exposure modes, such as spot metering, average metering, matrix metering, etc. What is exposure metering? What is its working principle and purpose? This point, I believe, many people know. However, single-lens reflex camera users need to pay attention that there are differences in exposure settings between taking photos with the camera’s viewfinder and using the electronic screen.
01、What is Exposure Metering?
The aperture, shutter speed, and ISO sensitivity work together to control the brightness of a photo. A larger aperture results in higher brightness. A longer shutter speed results in higher brightness. A higher ISO results in a brighter photo. The external environment’s brightness is constantly changing, right? Noon is brighter than morning, sunny days are brighter than cloudy days. After the camera is turned on, it will continuously “measure” the brightness of the external “light”, thus giving a combination of aperture-shutter-ISO values to ensure that the taken photo’s brightness is normal. When taking photos in M (manual) mode, exposure metering is useless because the aperture, shutter speed, and ISO sensitivity cannot be automatically adjusted at this time. Only when the camera can automatically adjust at least one of these items does exposure metering make sense.
02、Exposure Mode Selection
Different exposure modes are actually changing the measurement area. There are those that measure the entire screen, some that measure a small part of the screen, and some that measure a single point. There are also those that measure the middle and surrounding areas separately with the middle accounting for the majority. The camera only ensures that the measured area’s brightness is normal, and it doesn’t care about other areas. For example, when you are taking a photo of a sunset, the sun only occupies a small part of the screen. If you only measure the sun, then the sun’s brightness is normal. If you measure the entire scene, most of the environment will be darker, and the camera will increase the exposure, causing the sun to overexpose. Different manufacturers have different names for this, but the principle is the same. Taking Canon cameras as an example, they are called evaluation metering, partial metering, center-weighted metering, and spot metering respectively. Other manufacturers also have naming methods such as average metering and matrix metering. For more details, please refer to this article: How to Choose Among a Camera’s 4 Exposure Modes? Teach You to Use Exposure Function Correctly!”
【来源】https://www.ithome.com/0/745/192.htm
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