What filters do you often need to play photography? What are their functions?

Uv mirror: many people use it, which can effectively reduce the intake of ultraviolet rays (but it doesn't work on cmos) and prevent the lens at the front end of the lens from falling off and being scratched. However, even the best uv will have a bad influence on imaging, which will reduce the image quality and increase ghost. Therefore, personally, uv is not recommended. Spending a lot of money on a uv mirror is actually equivalent to spending money to reduce the imaging quality of your baby's lens, which does more harm than good. On the contrary, wearing a hood often can also prevent the lens from being scratched and inhibit glare to a certain extent, so the hood is harmless to the lens and imaging and will not damage the image quality.

Polarizer (CPL): the first choice for landscape photography. As we all know, reflected light is polarized light, which can be eliminated by a polarizer, so that things behind the reflective surface (such as things behind the glass window) can be easily photographed, and the color saturation of the subject can be increased because of reflection (such as the sky becoming bluer). But if it is used in portrait photography, it will have a bad effect: it will eliminate the reflection on people's faces and have no sense of hierarchy.

Medium gray filter (ND filter): It is also the first choice for landscape photography and other subjects. The purpose is to reduce the amount of incident light without changing the original color of the subject, so as to achieve the effect of slow door shooting (such as flowing water like satin, the trajectory of clouds in the sky, etc.). ), and it plays a very important role in shooting backlit portraits with flash without high-speed shutter synchronization. ND filter has this different dimming iNDex, that is, nd value. By analogy from ND2 to nd32, nd2 can only weaken the exposure of 1, ND4 can weaken the exposure of 2, ND8 can weaken the exposure of 3, and so on. I think the most commonly used medium gray filter is ND8, but CPL can also reduce the exposure of 1-2 files. So, it's up to you whether you want this neutral gray filter or not.

Medium gray gradient lens: This filter is a derivative of the medium gray filter. Its characteristic is that half of the lenses are 18% gray, and the other half is really colorless and transparent, and there is a transition at the junction between them. Its function is to balance the picture with excessive light ratio, such as the scene containing both the ground and the sky. If the light is measured by the ground, the sky will be too violent and dead white. If the sky is used to measure the light, the ground will be underexposed and become a silhouette effect. The medium gray gradient lens will appropriately weaken the exposure of the sky, and at the same time, it can roughly meet the exposure of the ground, so as to pursue the balance between the two exposures without losing the details of the dark and bright parts. However, using HDR technology and "black card jitter" (this technology can be obtained by Baidu, so I won't say much here) can also achieve this effect, even better than the effect of medium gray gradient mirror. So this filter is not commonly used, you can try it if you are interested.

Various color temperature filters and color temperature gradient mirrors: These filters used to be commonly used in film cameras, and they can adjust the white balance by changing the color temperature. However, in the digital age, these things are no longer commonly used, and occasionally someone will install or shoot some special scenes to enhance the color (digital later stage is also possible). If you are interested, you can buy some pieces from Taobao to experience it. Not worth buying.

That's all. I hope it helps you. My level is limited, please don't spray if there is any incompleteness or omission, thank you.