Lens filters are a big part of a photographer’s arsenal, and although they bring a great many uses to the table, many people wonder if they have a negative impact on image quality.
In fact, whether lens filters affect image quality or not is arguably one of the most debated topics in photography. Many tests have been carried out to try to find a definitive answer to this hotly-contested question.
Most ‘before’ and ‘after’ filter shots used for comparison testing actually prove that lens filters don’t adversely affect image quality. Some critics argue that placing an extra layer of glass in front of your lens causes problems. They suggest that it impacts on image clarity, sharpness and resolution, and can cause ghosting and flare. However, tests consistently fail to confirm these theories.
It’s worth pointing out that not all lens filters are created equally, however. Using a low-grade filter is more likely to harm the quality of your images compared to a really high-quality one. For instance, poor quality filters have been shown to sometimes introduce colour casts.
Additionally, how you look after your lens filter can impact image quality. A dirty, scratched filter will do more damage to your photos compared to a cared-for, spotless filter, for example.
The benefits of using a lens filter far outweigh any concerns you might have over image quality, however, and they’re a must-have if you shoot outdoors or under different or challenging light conditions.
A UV lens filter, for example, offers great protection for your camera lens and can reduce haze from your shots on a sunny day. A polarising filter will banish reflections, boost image clarity and enrich colours, and is invaluable for any photographer taking images of water, sky or foliage. An ND lens filter is a real asset to anyone taking photos in bright light, as by altering light exposure, it enables the photographer to add smooth, silky effects to water, enhance the colour of sky, clouds or foliage, whilst blurring or distorting moving objects.
Many of these effects created from using lens filters enhance image quality. But they also allow the photographer to add creative and unique touches, which can’t be replicated in post-production editing. Certainly, the visual improvements from using lens filters are greater than any negligible or unfounded negative impacts on image quality.
Understand your filter
Of course, one way in which lens filters could harm your image quality is if you don’t use them correctly. Therefore, understand how they work properly before heading out on the field. For instance, vignetting (where an image’s edges aren’t the same colour as the centre) can occur using certain filter scenarios. This is especially the case with a wide-angle lens. Or, when using variable ND filters, extreme f-stop densities can create an unwanted X mark on your image. Going a bit crazy with filter stacking may also degrade the quality of your image, so combine filters with care.