How to use optical zoom?

What is the optical zoom factor? First of all, make clear what is optical zoom. Optical zoom refers to the focal length range of zoom lens (different from fixed focus lens) on the premise of ensuring clear image. Any lens that indicates the range of focal length change is a zoom lens. For example, Olympus's 14-45 lens is marked as follows: 14-45MM, and the distance from the focus of the lens to the photosensitive element can be adjusted from 14MM to 45MM, which can clearly image. Beyond this range, nothing can be done. If this lens is converted into the parameters of the traditional 135 camera, it is 28. Then the imaging focal length 45 of the telephoto end divided by 14 of the short focal end (wide-angle end) is about 3.2 1. This is the optical zoom multiple, which is generally interpreted as an integer in the manual, indicating that it is 3 times optical zoom. For some reasons, it cannot be said that the larger the optical zoom factor, the better. See what you need. If you use it at home, you can basically say so. Not necessarily, if you are a professional or an amateur. The larger the optical zoom factor, the larger the distant object can be photographed without sacrificing the image quality (theoretically). But for professionals, if you want to shoot distant objects, you can use a long focal length lens, which can not only shoot the distant objects bigger, but also achieve special effects such as blurring the background. If you want to shoot a big scene and make a photo fit more content, you can use a wide-angle lens, which is better.

So what is the difference between optical zoom and digital zoom? Digital zoom means that a digital camera uses its own image processing system to cut a small piece on the sensor, add pixels through interpolation and forcibly enlarge it. What's the point? Isn't it the same if you enlarge the picture on the computer yourself? Therefore, digital zoom should be called digital magnification, which is not a real magnified image obtained through the change of lens focal length, and the more magnified, the less clear the image quality is. Therefore, some indicators should not be considered when buying a camera.

Theoretically, when distant objects are photographed at close range, the image quality will not be damaged. But it is actually a loss, and the main factors are: dust, air and stability. Dust will cause the light emitted by the target object to diffuse, and air may cause the light to refract, which will affect the imaging quality. The farther you shoot, the less clear and gloomy the picture is. There is also the stability of the camera, because the camera will shake slightly if it is far away, which can be solved by tripod and short shutter time.