Excuse me, what is the meaning of several times optics in photography?

Optical zoom multiple refers to the zoom ratio of digital camera lens. As the name implies, glass lens is a medium for "magnifying" optical imaging, and it is almost like a telescope when using high zoom. Although the imaging principle of camera optical lens is the same as that of telescope, the resolution of optical lens is many times higher than that of telescope, especially in digital camera. The higher the pixel, the higher the resolution of the lens. Therefore, it is very difficult to manufacture a large zoom optical lens, and the cost of the lens increases accordingly.

Generally speaking, 3x optical zoom is most suitable for home users and beginners, because these users mainly photograph people's lives. Since it is a home user, general shooting is enough. As we all know, in fact, when many people go out to take pictures, a 38mm fixed-focus fool camera is enough; If you have three times the optical zoom, it will be even more powerful, so the price of the whole camera will not be too expensive.

For photographers, 3x optical zoom is not enough. What is needed here is not only zoom, but also wide angle and telephoto. The smaller the focal length of the lens, such as 28mm, the wider the shooting area, which can achieve good visual impact on both the scene and people; If you use telephoto, for example, after adjusting the focal length to 200mm, you can shoot farther, so that the more subjects you shoot, the more distant things you can zoom in through the lens. Birds and beasts, things far away that can't be photographed at close range can be seen at a panoramic view. This is the advantage of telephoto lens, which is more expensive.

The aperture of a digital camera, like a traditional camera, is placed in several lenses of the lens and consists of several metal sheets, and the aperture is adjusted by the movement of the metal sheets. Anyone who has used a traditional reflective camera knows that we can find the aperture value f on the lens. Usually the aperture scale is:1.4,2,2.8,4,5.6,8, 1 1,16,22 ... The larger the aperture series f, the larger the lens. F value is the number obtained by dividing the focal length of the lens by the aperture (aperture size), so the larger the value, the smaller the aperture. Shutter speed values are usually marked as: 1, 2, 4, 8, 15, 30, 60, 125, 250, 500 ... These are the reciprocal of 1 second, so 15 means 650. Like the aperture, the shutter speed is twice as different per frame. For example, the shutter light value of 1/500 seconds is half that of 1/250 seconds and 1/4 of1125 seconds.