Some common sense about the lens:

Lens

The lens is a structure that gathers light so that the film can obtain a clear image. Early lenses were composed of a single convex lens. Because of poor resolution, chromatic aberration will occur, and it is gradually improved into a compound lens, that is, a combination of multiple concave and convex lenses to correct various aberrations or chromatic aberrations, and by coating the lens (coating) processing , Increase the amount of light entering, reduce the flare, so that the quality of the image is greatly improved.

Generally speaking, the lenses used for photography are focusing lenses. According to the optical principle, after the light from a distance passes through a lens with a focusing effect, they will all focus on one point, which is the focus. The distance from the focal point to the center point of the lens is called the focal length. On the camera, the center point of the lens is usually located at the aperture, and the focus is on the focal plane (ie the film surface). Therefore, the focal length of the camera is the distance from the aperture to the film when the lens focuses at infinity.

Types of lens (classified according to application)

· Wide-angle lens: The angle of view is more than 90 degrees, the observation range is large, and the nearby image is distorted.

· Standard lens: The angle of view is about 30 degrees, and the range of use is wide.

· Telephoto lens: The angle of view is within 20 degrees, and the focal length can reach tens of millimeters or hundreds of millimeters.

· Zoom lens: The focal length of the lens is continuously variable. The focal length can be changed from wide-angle to telephoto. The longer the focal length, the greater the imaging.

· Pinhole lens: used for concealed observation, often installed in places such as ceilings or walls.

Wide-angle lens

Wide Angle (Wide Angle), also known as short-focus lens. The wide-angle lens has a very short focal length, so the scene projected on the film becomes smaller. The wide-angle lens shooting angle, in addition to shooting more scenes, can also shoot wide-angle images in a narrow environment.

Wide-angle lens

A wide-angle lens is a photographic lens whose focal length is shorter than that of a standard lens, whose angle of view is larger than that of a standard lens, whose distance is longer than a fisheye lens, and whose angle of view is smaller than a fisheye lens. Wide-angle lenses are divided into ordinary wide-angle lenses and ultra-wide-angle lenses. The focal length of the ordinary wide-angle lens of the 135 camera is generally 38-24 mm, and the angle of view is 60-84 degrees; the focal length of the ultra-wide angle lens is 20-13 mm, and the angle of view is 94-118 degrees. Since the wide-angle lens has a short focal length and a large angle of view, a large area of ​​the scene can be photographed within a short shooting distance range.