For digital shooters, the main reason to use a UV filter is to protect the front element of the lens. Digital sensors are largely insensitive to UV radiation. With a UV filter on, you can avoid having to wipe the lens directly. It is also a cheap solution to scratches. This sort of protection is especially essential for shooting in the rain or in violent situations, for example.

Can a camera detect UV radiation?

Yes, though in negligible amounts. Most modern cameras and lenses have built in mechanisms to filter out unwanted UV radiation from being recorded in the sensor, which otherwise results in a hazy, unsharp image. This is more of an issue with film, which is much more sensitive to UV radiation, than digital sensors.

The technical answer to this question is yes, sensors can be sensitive to UV radiation.

And if you are interested in that matter, there are cameras especially created to shoot pictures with UV radiation as opposed to visible light.

But UV radiation is hardly a material issue today for digital cameras because they have internal mechanisms to cut out UV radiation, through lens design and having filters embedded on the camera sensor.

In practice, UV radiation almost has no effect on digital sensors.

Are UV filters worthless?

No. While it may not do what it claims to do, it is an effective way of protecting expensive glass. Whether or not you are interested in having your lenses protected is another issue, but many are of the opinion that having a UV filter on at all times is a relatively inexpensive damage insurance for their lenses.

As explained above, modern digital cameras rarely present the need for extra protection against UV radiation in form of a front-of-lens filter.

Doing a search through Google, though, would yield results purporting to show you the differences before and after using a UV filter.

While I am in no position to question the faithfulness of representations as such, they provide no proof either of how exactly the two images had been treated.

Based on my experience, in relation to digital photography, the effects of UV filters on image quality are negligible, if not making it worse.

All we know is that from a theory standpoint, there is not a great need for UV filters on lenses in the first place.

But that is not enough to say that UV filters are useless; lens protection is arguably the primary reason photographers still buy them today, in the digital era.

As we will see in the following section, UV filters are a cheap solution used by many professional photographers to prevent their lenses from being scratched or wet.

Ideally, you should not be in a position to have to clean the front lens element directly.

Do professional photographers use UV filters?

It depends on which sub-industry they are in, some presenting a greater need for a protective filter than others. For certain genres, such as press, landscape, or even food, where there is a realistic chance of wetting or dirtying the lens, UV filters are an easy solution. If photographic film is their main medium of output, they also most likely use UV filters.

Filters in general, including UV filters of course, cannot protect the lens from extreme violence. For instance, if you are to grab the camera and throw it at a brick wall, it would be shattered to pieces.

A UV filter simply cannot do anything to this level of damage; you will need to insure your gear all together to hedge against situations like these.

But that aside, such accidents being relatively rare, filters do go a long way to protect lenses against minor damages, which in contrast are much more commonplace.

The fact that you are mainly cleaning the filter not the lens itself makes a difference; if your gear ever gets wet, when shooting in the rain for example, you are wiping the water marks off of the filter not the glass.

That is one effective way of reducing the chances of scratching the lens.

I’ve also been in situations where people were not afraid to touch my gear - police pushing photographers away from key persons.

If you ever have to wipe fingerprints, or any type of grease, it would be 100 times better if it’s done to a filter rather than the actual lens element.

Practically speaking, UV filters, or filters in general, does two things. Firstly, it protects the lens, which basically protects your income if this is what you do for a living.

Secondly, it maximises your chance of being resell the gear as used at a decent price, which is what photographers commonly have to do when upgrading systems.

Does a UV filter affect image quality?

To a largely negligible degree, if UV filters do affect image quality at all. In most photo situations, the difference in quality is hardly noticeable between one taken with a UV filter and the other without. It doesn’t drastically improve the quality because digital sensors are largely insensitive to UV radiation, nor does it drastically degrade quality, similar to shooting through a clean slate of glass window.

If your images demonstrate a critical lack in quality, the filter on your lens is definitely not the first thing you should be worrying about.

What I managed to gather from forums and reviews is that there is no conclusive evidence pointing either way.

This tells you that while you cannot be sure that there are no effects at all, any effect it has is hardly material.

Should you get a UV filter or a polarizing filter?

On digital cameras, a polarising filter will be more useful. On film cameras, both filters perform different functions; this is not an apple-to-apple comparison. UV filter improves sharpness by cutting out haziness; polarising filters cut out reflections where unwanted. For digital cameras, UV filters aren’t as functional as digital sensors are not very sensitive to UV. Both filters offer lens protection.

In relation to digital systems, personally I prefer having a polarising filter on. It makes more sense from a cost-effectiveness point of view. Both filters offer options at various price points, so you will be able to get each with any given budget.

But the difference is that UV filters do nothing for you, because digital sensors are basically not sensitive to UV radiation; polarising filters minimise reflections.

This is not to say that reflections are always undesirable. But I know the filter has some sort of utility rather than just being a piece of glass that definitely won’t do anything under any situation.

My EF 24-70mm always has a circular polarising filter on.

For the type of work I do, I will need a filter to offer some basic protection to my lens. So the logic is that if I am to spend money anyway buying a filter, I might as well get a filter that actually does something else for my lens.

So if I were you, I would hands down go for polarising filters if shooting digital.

For film, as I said, you can’t compare the two.