UV Filters on a DSLR Lens– Do you need one?

The Facts and the Fiction behind UV Filters

OK, first and foremost, this is not a definitive article, it is not going to tell you 'Yes you need one' or 'No they are rubbish'. What it will do though is try and provide some sort of guidance as to when, as a photographer, you should consider using one. For the purposes of this article we are going to consider their use combined with a DSLR only. Their use with film SLR’s is a different topic altogether and outside the scope of this article.

OK, Fact 1: Using a UV filter on a DSLR will have absolutely no effect in terms of ultra-violet light reduction. You might as well buy a plain piece of well manufactured glass as it will give the same result. If you are photographing at high altitudes where UV haze is more noticeable I believe there may be more of a case for using a UV filter but for the majority of us, the use of a UV filter over a high-spec protective filter on a DSLR is a waste.

Fact 2, if you use a UV Filter on a DSLR you are going to cause some level of image quality degradation. This is an unfortunate optical truth. The levels of degradation will depend on the quality of the UV filter and whether it is multi-coated or not. Multi-coated filters tend to reflect less light and ensure more light actually passes through the filter reaching your sensor, providing better contrast and saturation in the resulting image. Cheap filters I have found to have more noticeable impacts on image quality whereas the more expensive ones don’t. However, image degradation is not just isolated to the use of UV filters, using any form of filter (Neutral Density, Polariser etc) will cause some level of image degradation simply because it is an extra piece of glass that light must pass through to reach the sensor. More glass is bad.

Filters may also cause increased flare when shooting against an intense light source such as the sun or an off-camera flash and though flares can sometimes be a nice addition to a photo, in a lot of situations you may want to avoid them. Ghosting and reflections may also occur depending on the quality of the UV filter. These need to be entirely avoided.

So, have UV filters anything going for them at all? Well, yep, they do and I gave a little hint earlier. They are fantastic for protection and even better for keeping your expensive lenses pristine clean and free of dust and dirt. In terms of low-priced lenses there is really no point in sticking a UV filter on it but where your lenses are professional grade then they are seriously worth consideration. A screw-in high-quality multi-coated UV filter will not only protect the expensive front element but it will also completely weather seal the lens. It acts as the first line of defence against airborne dust, dirt and moisture. Most of us have taken photos on the beach at some stage. Beach shooting conditions are usually far from ideal. It is highly probable you will end up with sand and salt on the lens front element. I don’t know about you but I wouldn’t like the thought of having to remove sand from my 70-200 f/2.8. What if I accidentally scratched the front element while cleaning it off? I think I would need counselling to get over something like that. Stick a top end UV filter (or protective filter) on the lens and you avoid all of this heartache. I, along with a ton of other photographers out there, cherish the lenses I own. Replacing a filter is a lot easier to do than replacing an expensive lens. For the small reduction I may have in image quality, I think it a fair price to pay for the peace of mind.

In terms of a reduction in image quality, what can you expect? Take a look at the following series of photos. These are 100% cropped images at 3 different focal lengths, with a UV filter and without. All photos are at f/2.8. This being the case, the effects of a UV filter should be more noticeable at the longer focal lengths because more of the filter area is actually used but as you will see from the photos below, the difference is negligible. And while difficult to determine the effects of image quality without seeing the full photo, with pro grade filters the reduction in image quality is minimal to none. Sharpness, saturation and contrast are all more or less identical. All photos were taken with professional Nikkor lenses (24-70 f/2.8 and 70-200 f/2.8 VRII) and a professional grade UV filter. All images have had zero post processing work done on them, just the crop.

Some pundits say your lens hood is sufficient to protect your lens. I say not always. On wider angle lenses they are not sufficient as the hoods are just too small. On longer focal length lenses a hood will do a better job, but it is not 100% protection. Just recently I was out photographing a street event with a telephoto lens. I had the lens hood attached and a UV filter on also. I noticed at one stage I had a big blob appearing in the photos. It turned out to be candle wax. How it managed to get passed the lens hood I will never know. Thankfully a quick switch of filters and I was back shooting again. Without a protective or UV filter this would have been impossible. A naked flame and some microfiber cloth got the wax off the filter without issue. I can’t imagine how I would have approached the clean if the wax was on the front element.

So for me, a UV filter is an essential purchase with every lens. They fully weather seal the lens and give me the peace of mind, knowing that whatever the shooting conditions, my front element is always safe. They are reasonably inexpensive so a small price to pay. A 77mm professional-grade screw-in filter can be picked up for the price of a night out, and although you don’t need to go for pro-grade filters for smaller aperture wide-angle lenses (less of the filter area is actually used) you are simply better off paying the extra bit and keeping all your filters pro-grade. As an added bonus, in terms of reselling lenses, you are far more likely to get buyers when they know the lens has lived its life fully protected. When a buyer sees a pristine front element then you shouldn’t have a problem selling on your gear.

In summary, there is no right and wrong. Some photographers hate them, some photographers swear by them. I am in the camp where I would prefer to use them in situations where there may be a risk to the front element of my lenses, which means anywhere outside the studio. If money is no object and image quality is everything then ditch the filter but if like me you prefer to minimise risk then a UV filter is the way to go.

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