Lens filter purpose explained and a look at the various types

A lens filter, also known as an optical filter, is a glass accessory that is placed on the front of a camera lens. Photographers use a variety of lens filters to alter how much light or colour enters the camera lens. This creates a number of desired effects, many of which can’t be replicated using post-production software.



The purpose of a lens filter largely depends on which filter you use. There are quite a number of different options to choose from! The type of photos you shoot may also dictate which filters you use and for what scene. Photographers working with challenging light conditions often make the greatest use of filters.


UV Filters

A UV filter, also referred to as a clear or haze filter, is mainly used to protect your camera lens from dust, dirt, moisture and scratches, so for this reason, you may choose to keep this lens filter on at all times. Modern digital cameras are able to block out UV light themselves. You’ll only need this filter to block out UV light on old film cameras or pre-2007 digital models. Having said that, some photographers find that a UV filter reduces haze and makes images sharper, even on modern cameras. If this filter gets damaged, it’s much cheaper to replace this than your actual lens. This last point alone is a good enough reason to use a UV filter.


Polarizing Filter

Polarising Filters

Another popular filter is the polarising filter, which is especially prized by landscape or outdoor photographers. The purpose of a polarising filter is to reduce polarised light that reaches the camera lens. This can cut out reflections from non-metallic surfaces. It’s a boon if you take photos of water, as it enhances the water’s details, even below the surface. This filter also reduces atmospheric haze on panoramic shots, providing greater depth of clarity. A polarising filter also increases the contrast and depth of colour in blue skies and the green of vegetation. This makes images so much more visually striking.



ND Lens Filter

ND Filters

Photographers who work in harsh light conditions revere another filter called the neutral density, or ND, lens filter. The purpose of an ND filter is to reduce the light exposure to your lens, so you can slow down your shutter speed and create images that are still sharp but not overexposed, even when the surrounding light is strong. By increasing exposure time, you can add smooth and silky effects to water shots, give drama to clouds and inject blur to fields of grass or moving objects, such as vehicles or people. If you use flash photography, you’ll also find an ND filter useful to achieve large apertures that avoid overexposure.




Graduated ND filters

Another type of ND filter that is commonly used is the graduated ND lens filter. This type of lens filter is clear on one end, slowly increasing in density towards its opposite end. The purpose of graduated ND lens filters is to even out images containing extreme variations in exposure on opposite sides of the frame. There are different types of graduated ND lens filters used for specific scenarios in landscape photography.

A hard-edge graduated ND filter is rectangular. Its purpose is to add clarity to very high contrast shots that have a flat horizon and a sky that is much brighter than the foreground. Where the horizon is not flat, such as shooting mountains or hills, you’ll find a soft-edge graduated ND filter more useful, as the soft edge enables smoother transitions so that images appear more natural.

In some scenarios, landscape photographers prefer to opt for a reverse graduated ND filter. This is particularly beneficial if you need to shoot against the sun when it’s on the horizon line, as this type of filter can create an even exposure balance between the sun and sky.


Gobe Yellow Filter

Colour or warming/cooling filters

Less commonly used in digital photography but more so for shooting videos, is a colour or warming/cooling filter, which can be used to adjust the white balance in a camera. Colour filters can either correct colour balance or reduce one colour and increase another. The effects created by this filter can be replicated using post-production software. This makes them less popular with digital photographers.


Special effects filters

Another filter that can also have its effects successfully reproduced using post-processing software is the special effects filter. This filter lets you get creative with your shots. So, if you want to add a dreamy appeal to images or make objects star-like, this filter does the trick.


Close-up filters

If you concentrate on macro photography, another filter you may find handy is the close-up filter. This filter essentially allows the photographer to get up close to a particular subject to focus in on the detail. Some photographers claim that this filter can impact on image quality. If you find this is the case, you may prefer to use a macro lens instead.

Whether you use a lens filter to create unique and interesting effects, to tackle challenging light conditions or simply to protect your lens, always get to know how to use a filter properly before taking any pictures. When purchasing filters, always go for the best you can afford. This ensures the highest quality image results. Remember to keep your filters clean and appropriately stored when not in use.