UV Filters

I’ve had a lot of questions recently about UV (Ultra Violet) filters and whether they were worth the investment and use on lenses. In the following article I attempt to address the main points for and against and to help you decide whether they are something that you want to use yourself.

What is a UV Filter?

A UV filter is a screw-in glass filter that is designed to block out ultra-violet light from your lens. It also provides protection from scratches and dust from the front element of the lens itself.

Protection from Damage

UV filters are primarily marketed as an additional form of lens protection – to help ensure that the front element of the lens does not get scratched or damaged. I regularly use lens hood attached to my lenses and whilst this usually provides for sufficient lens protection, I have directly experienced a stone crack a filter on my lens which saved the element from permanent damage. Whilst this wasn’t a UV filter, (it was a circular polarizer), the protection to the front end of the lens was still a huge benefit. Yes I was lucky that the broken filter didn’t damage the front element of the lens and as it wasn’t bucked I was able to carefully unscrew it to remove it. There is an argument that keeping a UV filter attached will protect your lens from similar mishaps albeit that they are so remote they can still prove extremely costly if you are unlucky. There are many times an uneven surface, strong gust of wind or even a damaged camera strap can lead to a dropped camera.

Protection from Dust and Other Extremes

UV filters can also provide arguably better lens sealing and additional protection from sand, dust and other contaminants from affecting the lens directly. Some lens manuals specifically suggest that an additional filter is required to provide full dust and water resistance to the lens despite being marketed as fully weather sealed. Again I think that this naturally depends on the particular environment in which you are shooting.

That said, it is also worth mentioning that cleaning a UV filter or a lens is pretty much the same thing and done in the same way as cleaning the front element of the lens – if done properly and with the right gear, there should be no damage to either.

UV Light

One thing that is not definitive or so clear cut is how much UV light would affect an image and how good the filters actually are in protecting from this.uv

It would seem that modern digital cameras are not affected by UV light in comparison to older film cameras, where the film was extremely sensitive to UV light. Personally I have not really noticed too much difference in my images in relation to tones or colour when using a UV opposed to removing it. In fact with cheaper brand UV filters there can actually be a slight degradation to the overall contrast.

Arguments against using UV filters

Flare and Ghosting

I often take photographs in the evening and dark when city lights are on. Whilst some lens flare is unavoidable in certain circumstances (such as shooting directly into a bright light) I have often found that cheaper UV filters accentuate this flare and make it worse. Sometimes, I have noticed that streetlights have been reflected from the lens onto the filter and then back into the camera and that this has been captured in the image.

Quality of the Filter and Loss of Resolution

There is a strong argument that the advanced technology that goes into the production of the glass within the camera lens should not be covered with a cheaper layer of inferior quality found in many cheaper UV filters. The front elements in many lenses are coated with special materials to help improve the quality of the images. It can be argued that putting a cheaper filter in front of this can only lead to the unnecessary degradation of the final captured image.

Cheaper filters may have some minute defects within in them that can degrade the final image quality. When photographing with a small aperture, these physical defects can often be visible in a final image.

Vignetting at Wider Angles

Vignetting is where you see darker areas in the corners of the final image. Wider-angle lens can be more susceptible to vignetting when a filter is placed in front of them. Naturally it is sometimes necessary to use filters such as neutral density (ND) or polarisers. It would seem that the best practice is to try not to stack filters and just to keep filter use to a minimum.

To Conclude

When deciding when to use a UV filter really depends where you will be shooting. This will play an important part in deciding if you need the additional protection or sealing to the lens itself. You also need to consider whether lens flare is going to be a bigger issue and affect the overall final images.

If you are going to be adding other screw in filters regularly, (like a polarizer), then you will be slowing down the process by having to constantly add or remove the UV filter as stacking multiple filters is not advisable or often necessary. Again this may bother some photographers more than others. Personally I do not find this to be much of an issue as it is relatively easy to remove a screw inflater even if just momentarily..

Lens hoods provide excellent protection for lenses and I recommend always using one. However, some may feel more comfortable with the additional layer of glass in front of their lenses in addition to the lens hood.

Ultimately whilst there isn’t a correct answer, I think that it is a personal preference whether or not to use UV filters. There are situation where they are advisable to use and to some the risk of damage may outweigh the time factors to consider in their use. What I do think is important is that purchasing your filters from a reputable brand is important as the cheaper lower quality filters may well introduce more issues to overall final image quality, especially at smaller apertures.

I hope that you find this article useful and naturally please feel free to contact me if you have any questions or comments relating to this topic or any other photography question.

Please also feel free to pass this onto any photographer friends that you think may find this useful.