Beginner photographers may see terms such as UV, CPL, and ND in magazines or the Internet. In fact, these are the filter names of photographic lenses. The lens that filter light is usually installed in front of the lens. Before the light enters the camera, some unwanted light is cut off to achieve some special effects. Let’s briefly introduce some common filters and applications now!

Ultra-Violet Filter-UV Filter

UV Filter can absorb ultraviolet rays, which is not great for most photos, but because it is cheap, many people also use this filter as a protective lens.

Neutral Density Filter-ND Filter

The dimmer mirror is actually a “gray mirror”, which is used to reduce the entry of light, allowing photographers to use slower shutter speeds than normal to shoot in early morning, evening, or a high-contrast environment (such as the bright foreground and dark subject) It is often used when shooting. Of course, when shooting waterfalls in daylight, you need to use a dimmer lens to slow down the shutter without overexposure to shoot a silky water stream. Some dimmer lenses will be adapted in the form of gradation, they are called “gray gradation mirrors”. The advantage of it is that they make the photos look natural and avoid the situation where the edges are not sharp.

Polarizing Filter (Polarizing Filter-PL Filter or Circular Polarizing Filter-CPL Filter)

The picture on the right is the effect of adding CPL (click to enlarge)

The picture on the right is the effect of adding CPL (click to enlarge)

Among the many filters, the most used are polarizers. Polarizers have two types: linear polarizers (PL, also known as linear polarizers) and circular polarizers (CPL Filters). Linear polarizers are often used on older cameras because they do not work with SLR cameras because of mirrors and metering/focusing beamsplitters. The circular polarizer can be used with any camera. The polarizer structure is composed of two lenses made of special materials, the angle of rotation is adjusted to eliminate the stray light in nature, so that the shooting theme presents a more realistic and full-color picture. Polarizers can make the sky bluer, eliminate reflections on the water surface, greener leaves, and add full natural colors. Polarizers play an important role in photography. Because polarizers have the function of reducing light, it can also be used as a light reducing mirror. For specific introduction and application of polarizers, please refer to future articles.

Infrared Filter


The infrared filter is used not to eliminate the infrared rays in the light, but to block the visible light, and only let the infrared rays pass through. The photos taken are like black and white photos but have unique colors and have the effect of perspective.

Softening Filter

The softening mirror can slightly blur the photo, making the photo have a hazy mood, which is common in portrait and flower photography.

Sky Light Filter-SL Filter

Skylights can absorb ultraviolet light just like UV filters, but skylights have another function of correcting color. Skylights are mainly used to adjust color temperature and take color photos in sunlight, which can obtain good color reproduction and high-purity photos. Especially when shooting outdoor portraits on a sunny day, it can prevent reflections caused by objects next to the person, so the person looks natural and real. But in the digital age, because cameras can adjust the white balance, basically few people now use skylights.

Black Card

The black card is not a filter, but any black card does not reflect light, it must also be used in front of the lens. It is used like a dimmer, mainly to reduce the amount of light entering a certain part, but because the shake of black card time is controlled by the photographer, so it is not affected by the value of the dimmer lens. It is often used to shoot sunrise, sunset, fireworks and night scenes. When using it, you need to use a tripod. The use of the black card can get very technical, so it requires more practice and detailed analysis. Please refer to future articles.


Author: Alex Tam