In this article, we will run through what a UV filter is, what its purpose is and whether you should use one or not. Read on for all the information you need.
What Is a UV Filter?
Ultraviolet (UV) is electromagnetic radiation with a wavelength from 10 nm to 400 nm, shorter than that of visible light. Primarily, it comes from our natural light source, the sun.
An ultraviolet filter stops these rays from hitting the film plane or digital sensor.
How Does a UV Filter Help Your Photography?
Cuts Out UV Light
Throughout the history of photography, films were mostly sensitive to UV light. It caused haziness or fogginess and in color films a bluish hue. The filters are transparent to visible light.
You may find the filters are referred to by two different names. A L37 filter removes ultraviolet light with a wavelength shorter than 370 nm, whereas an L39 filter eliminates light shorter than 390 nm.
Removes Blue Cast
The benefit of these filters is that they have a complete lack of effect on exposure. They also reduce and eliminate the blue cast that comes with the UV light, creating a better and more realistic overall white balance of the scene.
Removes Chromatic Aberration
The filter can also remove chromatic aberrations for certain lenses. The purple fringing of longitudinal chromatic aberration only occurs in particular circumstances.
This shouldn’t be confused with the much more common colored fringing caused by lateral chromatic aberration (most noticeable in the corners of the frame).
Protects The Lens
The great thing about a filter at the front of your lens is that it acts as a barrier. Not only to dirt, dust and smudges, but also to serious bumps and damages.
Dropping a lens on its front will smash the glass, and that can be a $20 filter or your very expensive telephoto lens.
Picture this. You are out taking photos and it starts raining. Your bag is out, all over the floor, and you have to collect all of your stuff scattered around.
You sling your camera on your back, throw everything you can into the bag, and head to the car. Working your way past some other cars, you run past a brick flowerbed, and that’s when you hear it.
Now, you have a huge scratch in your glass. Thankfully, you have your UV filter on, saving your expensive lens and only destroying your filter. That is a fair trade-off in my book.
Disadvantages of Using a UV Filter
Extra Cost, Weight, Problems
Having a UV filter on a DSLR isn’t really necessary for cutting out UV light. Digital cameras have been treated to be largely insensitive to these particular wavelengths.
Filters also need careful attention for cleaning, can trap dust between itself and the front glass element of the lens. And they cost money and they add weight to your already heavy system.
Loss of Quality
There are some filters that have been specifically designed to be used with UV filters. Some photographers have reported a loss in quality, and others haven’t noticed a difference.
Flare and Ghost Images
Adding more reflective items to your lens has the capacity to add more surface to bounce light from. A UV filter can pick up stray light and bounce it back. They may even create ghosts in very direct light.
Lenses already contain 15 glass elements inside, so adding more doesn’t help, but exacerbate the situation.
Loss of Light
UV filters come in all kinds of price ranges, and therefore, all kinds of quality. A low-quality UV filter can have adverse side effects, such as reducing light. Photographers like using these filters as they don’t have an effect on the light.
But as all glass elements in the lens do have an effect, its hard to image the filters don’t. Perhaps the higher-end filters do stop the light, just not noticeable by the naked eye.
Loss of Resolution
Some photographers have also reported a loss in resolution. I have never seen any instance of this. However, filters that do not have an optically flat surface, such as low-end UV filters, can disturb the direction of the light rays.
This can be a problem and intensified if using a telephoto lens due to its magnification.
There is basically no argument for the use of UV filters. Digital cameras no longer requires them, they are an extra cost and need attention, especially when it comes to cleaning.
On the flip side, there is no argument for not using them either. They can protect your lens, and they don’t reduce the exposure or resolution of your image.
If you are using expensive lenses in situations that could be very people heavy, where the landscape is unforgiving or otherwise, use one. Even better if you already have own one, as it incurs no extra cost.
If you need to buy one, make sure it is of high quality to ensure your images are not affected by it.
Read our full guide to lens filters for more more information!