What is the difference between the filters of SLR? How to choose?

Commonly used filters for SLR lenses are:

1, protective filter, such as protective mirror, UV mirror. UV mirror has the function of filtering ultraviolet rays, but the sensor of digital camera is not as sensitive to ultraviolet rays as photographic film, so there is no need to filter ultraviolet rays, and UV mirror has strong transmittance, which is usually used to flexibly protect the front lens of the lens.

2. The circular polarizer (C-PL) is mainly used to overcome the harmful reflection of glass, water and leaves (for example, when taking photos of cultural relics in the glass showcase of a museum), and also has the function of enhancing the color depth of the blue sky, so taking photos of the blue sky and white clouds will have stronger expressive force. As shown in the figure, use polarizer to increase the expressive force of blue sky and white clouds.

3. The gray gradient lens is suitable for shooting scenes with particularly strong light ratio in the upper and lower parts of the picture. For example, when shooting sunrise/sunset, the sky is bright and the horizon is too dark. If you take care of the exposure in the upper part of the picture, the lower part of the picture will be unclear. At this time, the dark part of the gradient lens can be used to darken the sky, and the bright part can relatively increase the exposure below the horizon. Gray gradient lenses have no effect on the white balance of the picture, and there are orange gradient lenses and blue gradient lenses to render ambient light. As shown in the figure, gray gradient+orange gradient effect.

4. Dimmers with different dimming levels: ND2, ND4, ND8........ND400. Used to reduce the shutter speed under strong ambient light. If you shoot running water with a slow shutter, you can create a silky effect. The antireflection mirror usually consists of two polarizers, which can reduce the light level when rotating, and is called variable antireflection mirror. The running water shot by the slow shutter is shown below.

5, starlight mirror, there are cross-shaped and rice-shaped points, is to carve a cross or rice noodle on the plane mirror. When shooting at night, the light source appears cross or herringbone star awn. The performance effect of this starlight mirror is too dull, and it is dismissed by professional photographers. With a small aperture and a slow shutter, you can also make a point light source appear at night.

6. Other filters that were almost eliminated in the digital age. Including the color mirrors of the film era (such as yellow mirrors and red mirrors). -Adjusting the color temperature or darkening the blue sky in black and white film can be completely replaced by adjusting the white balance in digital cameras), soft lens (soft light effect can be completely formed in post-production of digital photos) and close-up lens (just a convex lens, which is easy to cause poor distortion and poor edge imaging).