Camera lens filters are very useful in photography and carry out a variety of different effects. Coloured filters are designed to allow the user to change the way colour is displayed on an image, depending on the type of colour being used, and are primarily used for black and white photography. Follow the guide below to discover how coloured filters are used and which ones suit which situation.
What is a Colour Filter
Colour filters are a very special element for a camera, particularly film cameras. They are absorption filters made of different coloured glass which absorb the light in various wavelengths in different degrees (depending on the type of filter) and allow other ranges of light in. Put simply, the principle of a colour filter is to absorb the white light source that is daylight and filter it by allowing certain colours through.
Filter glasses come in red, green, orange, blue, or yellow, with some specialist lenses such as neutral density also offering a different tone of colour.
Types of Coloured Filter
- UV or Ultra-Violet
- Neutral Density (ND)
- Colour Conversion or Correction
- Colour Compensating
Yellow filters offer a boost to the contrast of an image, and are popular in portraiture photography as they can be used to cover blemishes on the skin. This type of filter is more subtle in its appearance and is popular with beginners as it can be used for almost all photography types.
Orange filters can be found either on their own, or as part of a colour conversion/correction lens (discussed in more detail below). This type of filter is usually used for landscape images to provide enhancement for clouds and other details against the background, and offer a medium contrast to the image. They are considered to be a nice balance between yellow and red filters and are often considered a general purpose colour filter. Skin is given a healthy and smooth look, while buildings appear softer and more pleasing.
Red filters are some of the most extreme as they provide a strong effect and are often used to give a dramatic image to architectural images and landscapes. Red filters should be used with care as the result can often be too harsh an image for most types of photography. If used correctly, however, the effects can be very striking. A red filter can turn a sky almost black in colour, and can be used to create visibility in foggy shooting conditions.
This type of filter is not commonly used but can be useful for photographing plants as it brings out the green of foliage amongst the other colours of flowers. Green can also be used for landscape images, but care should be taken to avoid negative effects on the sky area.
Rarely used in photography, blue creates a vibrant contract and cold tone to images, which can be very effective in the right type of shot. Blue filters are usually used for a mood enhancer on landscape images.
Although technically clear filters are not filters at all as they do not change the light, clear lenses do provide some benefits. A clear filter on the lens protects it from dust, fingerprints, scratches, or other forms of damage. If the lens is dropped, the filter will provide it with some protection from breakage. As a clear filter is relatively expensive in comparison to that of a new lens, it can be a good investment for a photographer.
UV or Ultra-Violet
The next step from a clear filter is a UV or Ultra-Violet filter. Ultraviolet light is invisible to the naked human eye; however, it can be seen on a film, where it shows as a blue-ish cast (which is an undesirable feature in most photography) or even has a blurring effect. While UV filters are often used as a means of protection for both the film and the digital lenses, this type of filter can be left on at all times since it is clear and does not change the colour or the density of the light. This type of filter is ideal for photography taking place in expansive outdoor spaces such as mountains or large sweeping landscapes.
Neutral Density (ND)
This is a popular filter for those who do a lot of outdoor photography. Neutral density filters are grey in colour and designed to reduce the amount of light that passes through a lens. The purpose of these lenses is to prevent overexposure or the images from becoming washed out when either the light is too bright or the ISO is too high. It allows the user to lower the intensity of the light so the camera can be shot at a slower shutter speed and achieve a blurring image on the image. It corrects exposure and at a wider aperture reduces the depth of field, which enables sharpness in the foreground of the photographs and a slight blur in the background for good effect.
Neutral Density filters are known as ND filters for short, and are available to purchase in various densities, which allows the user to control the filtering depending on the lighting conditions at the time of shooting.
Colour Conversion or Correction
All film has a colour balance (also known as a temperature) which is designed to suit a set of lighting conditions. Daylight film is intended to give correct colour for photos that are taken in normal daylight lighting conditions, whereas tungsten film gives correct colour under warm tungsten light (which is the light of normal household bulbs). There may be time when a photographer does not have the right film in their camera for the lighting conditions that they are shooting in. This is where colour conversion/correction filters can be used.
These types of filters remove unwanted colour casts and ensure that the colour is rendered correctly. They are primarily used on cameras that require film, not digital cameras. There are two forms of colour conversion/correction filters - orange and blue. Orange filters of this type warm up scenes that are too blue under normal conditions and give them an orange tint, whereas blue filters of this type cool down scenes that are either too orange or too red. The filters in this type can vary in their strength, and they are very precise in how they shift the colour. The measurement used to determine both the colour cast and its strength is called degrees Kelvin. A basic rule of thumb is that the higher the number, the bluer the colour is and the lower the number, the warmer the colour is.
Although these type of filters are normally used on film cameras, they are sometimes used on digital cameras that have an automatic white balance with no manual option. They are not required on digital cameras that have a manual colour temperature selection built-in as the colour can be set internally by the camera, so no external filters are required.
These type of filters can be cyan, magenta, or yellow in colour and absorb different levels of red, green, and blue sections of the colour spectrum. This is done in order to correct any deficiency in the colour quantity of light source and reduce any unwanted rays and reflections that are intrusive on the final photograph.
There are several different types of coloured filters available on the market, all of which carry out a different effect on the photographs that are taken. Sufficient research should be conducted into the right kind of filter that is required before a purchase is made. Coloured filters can change the entire mood of a photograph, so for some types of photography, they are a great investment to make.