夜景照片常常出现在我们的相册中，其中一个有趣的现象就是楼房上出现的圆圈。这些圆圈是由什么引起的呢？为了解答这个问题，我们需要了解一些基本的摄影原理。

在夜间拍摄夜景时，摄影师通常会使用较长的曝光时间来捕捉足够的光线。当光线进入镜头时，它会通过光圈控制器，调整光线的亮度和对焦的深度。光圈是一个圆形的开口，可以调节大小，以便控制进入镜头的光线量。在夜景摄影中，摄影师通常会选择较小的光圈，以获得更大的景深，让整个画面保持清晰。

然而，当光通过较小的光圈时，会遇到一个现象称为"衍射"。衍射是指光线经过一个小孔或障碍物时，会发生弯曲和散射的现象。在光线通过光圈时，它会发生衍射并形成类似圆圈的模式。

这些圆圈的数量取决于光圈的直径和光线的波长。通常情况下，较小的光圈会产生更多的圆圈，并且圆圈的大小与光圈直径成反比。此外，不同波长的光线会形成不同大小的圆圈。因此，当摄影师使用较小的光圈和不同波长的光线拍摄夜景时，楼房上的圆圈就会出现。

这些圆圈的出现并不是缺陷或错误，而是摄影过程中的自然现象。事实上，它们给夜景照片增添了一些独特的魅力和美感。有时候，摄影师甚至会刻意利用这些圆圈来创造艺术效果，使照片更加引人注目。

总结起来，楼房上出现的圆圈是由于光线通过较小光圈引起的衍射现象。这些圆圈的大小和数量取决于光圈的直径和光线的波长。尽管这些圆圈并非意料之外，但它们为夜景照片增添了一些独特的魅力和美感。

Nighttime photos often find their way into our photo albums, and one interesting phenomenon in these pictures is the appearance of circular shapes on the buildings. What causes these circles to appear? To answer this question, we need to understand some basic principles of photography.

When capturing night scenes, photographers often use longer exposure times to capture enough light. As light enters the lens, it passes through the aperture, which controls the brightness and depth of field. The aperture is a circular opening that can be adjusted to control the amount of light entering the lens. In nighttime photography, photographers typically choose smaller apertures to achieve greater depth of field and maintain a sharp image.

However, when light passes through a smaller aperture, a phenomenon called "diffraction" occurs. Diffraction refers to the bending and scattering of light as it passes through a small hole or obstacle. When light passes through the aperture, it diffracts and forms circular patterns.

The number of circles depends on the diameter of the aperture and the wavelength of the light. Generally, smaller apertures produce more circles, and the size of the circles is inversely proportional to the diameter of the aperture. Additionally, light of different wavelengths will create circles of different sizes. Therefore, when photographers use smaller apertures and light of different wavelengths to capture night scenes, the circles appear on the buildings.

These circles are not defects or mistakes but rather natural phenomena in the process of photography. In fact, they add a certain charm and aesthetic appeal to nighttime photos. Sometimes, photographers even deliberately use these circles to create artistic effects and make their photos more captivating.

In conclusion, the circles appearing on buildings are caused by diffraction as light passes through a smaller aperture. The size and number of circles depend on the diameter of the aperture and the wavelength of the light. Although these circles may not be expected, they add a unique charm and aesthetic appeal to nighttime photos.