What is the Purpose of a Camera Filter?

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What is the Purpose of a Camera Filter?

A Camera filter, or an optical filter, is a camera accessory which helps adjust the flow of light that reaches the camera sensor or the film. Lens filters are used either as standalone equipment or in combination with other items to achieve certain special effects that are usually beyond the scope of photo editing. There are several types of camera lens filters available, and their choice is based on the type of photography, lenses used, and effects one is looking to create, apart from the budget and time and the effort needed on post production edits.

It is important for amateurs and hobbyists as well as professionals to first know the types of camera lens filters available in the market. They must know how they work and their intended purpose before shopping for suitable lens filters to enhance their creations.

Camera Lens Filter Types

Lens filters are available in different types, each working in its unique way to enhance the image quality.

Polarising Filter (Linear & Circular Polarisers)

Cuts down the amount of light that reaches the camera film or the sensor. Autofocus and metering systems are both usable on circular polarisers. Cheaper linear polarisers, however, are not usable with through-the-Lens (TTL) metering system or autofocus on DSLRs.

Increased colour saturation. Minimised glare or reflections from polished surfaces, glass, water, bright light, or heat. Enhanced contrast between various elements in the image.


Neutral Density Filter

Reduces both the amount of light and intensity of the colour entering the camera to eventually reach the sensor.

Smoothing movements and blurring the main image according to the surroundings.


Graduated Neutral Density (GND) Filter

GND Hard Edge, Soft Edge, and Radial blend or centre-sport filters

Irons out the exposure and colours across the image. Hard edge variant provides a sharp division based on the brightness of colours. Soft-edge filter ensures a smooth blend of colours fading into each other. Radial blend helps enhance or cut down vignetting at the edges.

Captures natural gradation of colours in an outdoor setting. Choice of variants should match the light effects to capture vivid colours.


UV Filter

Cuts down haziness caused by UV light.

Clear images on conventional film-based SLR cameras.


Colour Filter

Enhances or exaggerates select colours in an image.

Alters the natural colour scheme of an image.


Cooling or Warming Filter

Adjusts the white balance in an SLR to improve the feel of the image.

Enhances or tones down select colours to add extra warmth or coolness to the picture on an SLR.


IR Filter

Blocks all visible light from the spectrum, allowing only near infra-red rays to enter the camera.

The images are devoid of natural colours used to improve special effects.


Star Filter

It is basically an etched filter with thin lines dotting the filter surface. Light from a single source is diffracted perpendicular to these lines.

Enhances the image using special etched patterns.


In addition to the above mentioned types, there are several other filter types that control light diffusion, tone, and contrast. There are filters that offer colour conversion, light balancing, and colour compensation effects as well. Special filters are also available for colour correction while shooting images under water.

Going by the function and the effects, it can be seen that not all of these lenses are suitable to all types of photography or even all types of cameras. UV and colour warming filters do not add any value to digital cameras, where sensors do not respond to UV light and do not need colour warming effects. This is because they can automatically correct colour balance to achieve the same effect. Similarly, only select lens filters are suitable for black and white photography.

Polarising Filter (Linear & Circular Polarisers)

Minimises reflection and improves saturation

Outdoors, natural settings, landscapes, water, and greenery


Neutral Density Filter

Long exposures with choice of both shutter speeds and exposure

Live action, flowing waters, landscapes, and busy streets


Graduated Neutral Density Filter

Controls blurs, adjusts exposures to capture bright lit landscapes

Landscapes, action and stills


UV Filter

Enhances clarity and is used mainly as a protective lens cover on DSLRs



Colour Filter and Cooling or Warming Filter

Enhances colour to capture image in the required tone

Special occasions, landscapes, and portraits


IR Filter and Star Filter

Special Effects

Night time cityscapes, portraits, and well-lit landscapes. IR is helpful to achieve an unrealistic, appealing yet eerie looks


Camera Lens Filter Fitment

Lens filters are simply an additional piece of treated glass between the subject and the camera lens, and they should fit snugly on the lens to render the intended visual effects. Camera lens filters are available in two different models: Front and Screw-On.

Camera Filter Models






46 mm to 82 mm size in diameter

Filter diameter to match the diameter indicated on front or top of the camera lens.

Snugly fit on the lens protecting it from any damage. Step up rings or step down lens adapters may be used to custom fit the same filter on multiple lenses. However, custom fits can cause vignetting if the filter edge interferes with the light entering the lens.




Usable with all cameras and lenses.

Larger filters that are not fit directly on the lens. Usually handheld in front of the lens. Cumbersome to use. Filter holder kits available for ease of use.


Using Multiple Camera Lens Filters

With each type of camera lens filter adding a unique dimension to photography, enthusiasts may choose to experiment with multiple filters to achieve a perfect shot. It is possible to simply stack up an array of lens filters ahead of the lens, thanks to the structure of the filter itself.
Lenses need not be lined up in any specific order; however, it is important to watch out for the combined effect so that, unless intended, the lenses do not in any way clash or negate the effects of each other.
Screw-on filters also sport threads on the outside, making it easier to simply fit another filter in the lineup. On the other hand, specially designed clips help fit multiple front lenses together.

Camera Lens Filters - Things to Watch Out For

Camera lens filters tend to affect image quality because of additional layer of glass over the lens, causing light to reflect off multiple surfaces, resulting in a lens flare. This may increase with the number of filters used for capturing a given image. Restricting the number of filters to about three will help manage this problem.
Vignetting, fuzzy, blurred images or edges are quite common if the camera filter size does not really match the lens, especially with the use of step-down adapters.


Experimenting with lens filters is a great way to take advantage of the play of light in nature, toning down and enhancing select aspects to add a personal touch to a shot or capture an image in its native setting. Choice of lens filters, their (re)usability, costs, etc. are basically driven by exactly what one is looking to create or record on their equipment. It also depends on the willingness of the enthusiast or professional to invest time and effort to enhance the image with novel effects that may not be possible to achieve through edits. Experiments, however, do pay off only with the right type of equipment, accessories, and attitude. Given the wide lens filter choices, it is possible for both hobbyists and professionals to now explore their interests in a cost-effective manner.

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