Calibration mirror of camera filter

Gradient mirror, this filter is constructed as a transparent lens at the lower part, and gradually transitions to other colors, such as gradient gray, gradient blue, gradient red and so on. It can be divided into gradient mirror and gradient diffusion mirror, and can be divided into soft gradient and hard gradient in gradient form. "Soft" means a large transition range, and vice versa, it means a small transition range, which should be chosen according to the creative characteristics. The gradient lens is often used in landscape photography, and its purpose is to ensure the normal tone of the lower part of the photo and deliberately make the upper part of the photo reach a certain expected tone. Gray gradient lens, referred to as GND lens for short, is widely used in gradient lenses, which transmits half light, blocks half light and blocks some light from entering the lens. It is mainly used to obtain the correct exposure combination allowed by the camera under the conditions of shallow depth of field photography, low-speed photography and strong light, and is also often used to balance tones. GND mirror is used to balance the contrast of the upper and lower or left and right parts of the picture, and is often used to reduce the brightness of the sky and the contrast between the sky and the ground. It can effectively darken the brightness of the upper sky, soften the transition between light and dark, and effectively highlight the texture of clouds while ensuring the normal exposure of the lower part. GND mirrors have different models and different grayscales. From dark gray to colorless. Usually, the contrast of the picture is measured before deciding to use it. Expose according to the photometric value of colorless part, and make some corrections if necessary. As for the color gradient mirror, there is a sunset mirror which is widely used. It is a transition from dark orange to light orange, which is used to enhance or create the sunset effect and express the dusk atmosphere in the shooting scene. When shooting, if the light is too strong, we have to narrow the aperture, but this leads to the failure to obtain the necessary exposure combination. If the ND mirror is used at this time, this problem can be solved. It can only reduce the amount of light passing through the lens and has no effect on the color tone. On the surface, the hue of this color filter is gradually changing from gray to black. The larger the number, the stronger the ability to reduce luminous flux. In addition, when there is a strong light brightness contrast in the picture, GND mirror can be used to obtain the balance of picture exposure.