The type is a key characteristic of any colour filter: it describes how it works and, accordingly, its application.
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Ultraviolet. The main function of such filters is to trap excess ultraviolet radiation, which reduces the quality of images and adversely affects camera matrices. They are designed primarily for shooting in the mountains or on the coast, where UV levels are higher than normal conditions: UV filters correct colour reproduction, eliminating excess blue, and increase contrast. In other conditions, such filters practically do not affect the quality of images, and therefore can be used as a permanent protection of the lens from moisture and pollution.
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Infrared. In this case, filters are meant that transmit only infrared radiation; shooting in this range requires a special film or a camera with a matrix that is sensitive to IR rays. IR photography is used both for scientific and technical purposes, and in artistic photography, since it allows you to get unusual effects (for example, the leaves of trees in the IR range may look white). In addition, different filters pass different ranges of infrared radiation, which gives even greater features in artistic experiments.
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Colour enhancer. As the name implies, such filters are used to emphasize a certain colour — for this, their glasses are painted in one colour or another. There are v
...ariants painted in several colours, they are usually used for various classic situations (for example, blue and green — “sky and grass”, “sky and forest”). In fact, colour enhancers are mainly used in professional colour photography, because you can easily reconfigure colours in a photo within certain limits due to post-processing in a photo editor.
— Colour balancing. A filter designed to change the overall colour balance of an image (this setting is also called “colour temperature”), see “Colour balance” for details. It is used mainly in film photography, because. digital cameras usually have their own colour balance adjustment tools.
— For b/w photo. A type of colour enhancing filter (see above) designed to provide contrast in black and white photographs. One of the peculiarities of b/w photography is that objects that are seen as contrasting in colour can practically merge in black and white images — for example, red berries against a background of green leaves. By applying a colour filter, you can emphasize the desired colour, making it lighter or, conversely, darker in a b/w image: for example, in this example, a green filter will make the leaves light and the berries dark. It is worth noting that, despite the apparent similarity, B/W filters are not intended to be used as colour enhancers in colour shooting, because have their own colour correction specifics (see below) — in particular, they affect the entire spectrum and introduce noticeable distortions in colour reproduction.
— Gradient. Filters with partially shaded or coloured glasses; the other part of the glass is transparent. Shaded (neutral grey) filters are mainly used to equalize the brightness and allow you to correctly convey the contrast in the entire picture if the areas being photographed differ greatly in illumination. This is especially true in landscape photography, where there are often bright skies and relatively dimly lit ground: by setting the gradient filter with the dark side up, you can get a high-quality shot by muting the glow of the sky. Colour gradient filters can be used as colour enhancing filters (see above) or for artistic effects. Often such filters have a design that allows you to change the height of the location relative to the lens.
— Polarized. Light filters equipped with polarized glass. Such glass has a number of properties that are useful primarily for landscape photography, including filming near the water. So, it partially eliminates glare and reflections, which helps to avoid blurring and makes water shots clearer, and the sky in the pictures through the polarizer looks more saturated. In addition, to a certain extent, such filters can even replace neutral ones (see below), because. allow for a longer exposure. Another area of their application is filming through glass (albeit in a certain range of angles).
— Neutral. Such filters have a "neutral" grey tint and are designed to reduce the intensity of the light flux without changing its spectrum. They are useful, for example, if you want to use a slow shutter speed to show movement effectively or an open aperture to blur the background, but the subject is strongly lit, and the sensor or film has too high a sensitivity. The ND filter saves the day by essentially providing a desensitizing effect.
— Softening. The softening reflected in the name of these filters is expressed in a certain blurring of the image. This can be used, for example, in portrait photography to smooth out skin texture, eliminate visible imperfections (blemishes, moles, etc.), and in other types of photography to create artistic effects.
— Protective. Such filters are designed solely to protect the front lens of the lens from moisture, dust and fingerprints. They are absolutely transparent, do not change the properties of the light entering the lens and do not affect the shooting in any way.
— Ray. Beam filters are designed to emphasize light sources: they create visible beams in pictures that radiate from these sources. This is achieved thanks to a special glass coating, with embossed grooves.
— Macro. As the name implies, they are designed for macro photography. Such filters are actually additional lenses that reduce the minimum focal length of the lens and allow you to get as close as possible to the object being shot.
— Coloring. Variety of colour filters; in accordance with the name, are designed to colour the image in one colour or another. At the same time, unlike colour-enhancing filters, they do not just emphasize their colour in the general variety, but completely "clog" all the others with it, and as a result, a picture is obtained in different shades of the same colour. This gives the appropriate features for artistic shooting — for example, you can simulate an alien landscape due to the effect of "ethereal" lighting.
— interference. Filters capable of passing only a certain part of the visible light spectrum. This is achieved due to the fact that their glasses are made from many ultra-thin layers of alternating materials with different refractive indices. The most popular way to use this technology is to create protective light filters that protect the camera from “extra” infrared and ultraviolet radiation: an interference “glass” effectively cuts off the light spectrum at the top and bottom edges, passing only visible light. Technically, an interference filter can also be a “colour” (coloring or colour-enhancing) filter, and such models have a number of advantages over traditional (absorptive) colour filters — in particular, good light transmission and effective suppression of “non-native” colour. However, for a number of reasons (in particular, due to the complexity of production), this option has not received much distribution.
— Foggy. A filter that creates the effect of slightly blurring a picture, for example, to create a romantic atmosphere in a photo. Fogging brightens the vast dark areas of the image and visually "unloads" them.
— Effective. This category includes filters designed to apply specific effects to photos and do not belong to any of the categories described above. The set of such effects is very diverse, it includes, in particular, a vignette (darkening of the edges), colour spots or imitation of strokes of paint, incomplete blurring of the background — a small part of the frame remains sharp, etc. The specific type of effect in each case must be specified separately.The dimming ratio indicates how many times the light filter reduces the intensity of the light flux passing through it. Each increase (ND) by 2 times means darkening by 1 exposure stop, respectively, the 4ND light filter attenuates the light flux by 2 exposure stops (x). It turns out 8ND — 3x, 16ND — 4x, 32ND — 5x and so on ... This parameter is important primarily for neutral filters (see "Type"). If after ND there is a large number (for example, 100 or more), it is logical that this is not a step (exposure value). To translate, you need to take the logarithm to the base of two.
