What is the principle of wide-angle lens in camera shooting?

Before introducing the wide-angle camera, let's know the focal length of the camera. In fact, when people talk about the focal length of a digital camera, they are not talking about the actual focal length of the digital camera, but about the equivalent focal length, that is, the focal length relative to the traditional 135 camera. From the principle of photography, the smaller the focal length, the wider the field of vision, and the wider the range of scenery that the photo can accommodate; The larger the focal length, the narrower the field of view, which means that you can shoot distant objects. In traditional cameras, wide-angle lenses over 28mm are very popular. However, due to the particularity of small photosensitive devices in ordinary digital cameras, the physical focal length of the lens needs to be very short to achieve a wide angle, which leads to high requirements for aberration correction and anti-glare coating.

The biggest feature of wide angle is that it can shoot a wide range, with exaggerated sense of distance and wide focus range. When using wide angle, you can enlarge the object in front of you and narrow the object in the distance, and the surrounding images are easily distorted. Wide-angle can also adjust any point in the image to the most appropriate focal length to make the picture clearer, which can also be called complete autofocus.

Wide-angle digital camera has short focal length, wide viewing angle and deep scenery, which is suitable for taking photos of large scenes, such as architecture and scenery.

At present, the world's smallest 28mm wide-angle digital camera is Panasonic's fx0 1 black body, which is a classic model. Nice appearance ~

wide-angle lens

That is, wide angle, also known as short lens. Because the focal length of the wide-angle lens is very short, the scene projected on the basement membrane becomes smaller and the shooting angle of the lens becomes wider. Wide-angle images can not only shoot more scenes, but also shoot in narrow environments.

After all, a wide-angle lens is a concave lens and a nearsighted lens. Someone in the jar has made a similar wide-angle lens, that is, a nearsighted lens, but the barrel distortion is great when it is made, and focusing will be troublesome. I have tried that lenses above S5500 degrees can only be focused in macro mode, and the edge of the picture is very virtual, and the phase difference and color difference are unacceptable.

The degree of concave lens in front of wide-angle lens plays a decisive role. If you want to eliminate barrel distortion, you need convex lens (that is, hyperopia lens) to cooperate. The wide-angle coefficient is equal to:

(1) degree of concave lens;

(2) Degree difference between concave lens and convex lens;

(3) the distance between concave lens and convex lens;

(4) The convex lens is related to the distance of the camera lens. There are many things we don't know.

Therefore, we can get our own satisfactory results by adjusting the above four items, in which (2) barrel distortion is avoided, and the smaller the degree difference between concave lens and convex lens, the smaller the barrel distortion is. (3) The wide-angle coefficient is determined without changing the degree of concave lens. The greater the distance, the smaller the wide-angle coefficient. In other words, the wider you look, the distance is not infinite. In fact, if you slightly exceed the' limit', the camera will have four dark corners. (4) Use a camera lens to avoid the reflection and diffraction of light.