A UV filter is a glass filter that attaches to the front of your lens and blocks the ultraviolet rays. They were needed for film photography, but now most photographers use them to protect their lenses.
There is a lot of misinformation about UV filters out there. Some photographers swear that they are essential, while others are also certain that they are a total waste of money. In some photography stores, sellers will not let you go with a new lens unless you've also bought a UV filter; in others, they will laugh you at the door if you try to buy them. So what is the truth? Let's find out.
What does a UV filter do?
A UV filter blocks UV light when it enters the lens. Think of it as a sunscreen for your camera. Some old photography films were very sensitive to UV light, so if you did not use a UV filter, you would get a blue haze on your photos. This was particularly common if you were filming somewhere, there was a lot of UV light, like a very sunny day or at high altitude. You can see it in this Polaroid by MoominSean on Flickr .
The fact is that modern movies and digital sensors are not sensitive to UV rays. It does not affect them like old movies. This means that you do not need a UV filter to block UV light in order to take good pictures. However, this has not prevented UV filters from taking secondary use as a protective filter for your lenses. Some camera shops are reluctant to let you out with a new lens, if you have not bought a UV filter to protect it.
Does a UV filter protect your lens?
The basic idea is that if you drop your $ 2,000 goal, instead of breaking the front lens element, you break your UV filter at 35 $ instead. It's a lot easier to just take a new filter rather than shipping your goal to-maybe repaired. Unfortunately, although the idea seems good in theory, it does not really work.
Steve Perry of the Backcountry Gallery tested a load of different filters and lenses and found that the filters added minimal or no protection.
Perry's big conclusion was that the glass in the UV filters was much lower than the glass used in the lens's front element so the filters would break drops that did not even dye a lens, whether there is a filter on it or not. In addition, if a lens was hit hard enough for the front element to be damaged, there were normally also large amounts of internal damage. Even in the rare cases where the UV filter could have protected the front element, the lens was dead anyway.
All of this means that if you drop your lens with a UV filter and the filter breaks but not the lens, all you probably did was break a filter. The goal would have been nice anyway. And if you drop your lens without a UV filter and it breaks, a filter would not have saved it.
This does not mean that UV filters offer no protection. It simply means that they offer no protection against hard falls. They are great for protecting your lens from dust, scratches, sand, spray and other small environmental hazards.
The optical effects of UV filters
There is one more thing to consider about UV filters: putting extra glass in front of your lenses affects the quality of the image.
UV filters block a small percentage (between 0.1 and 5%) of the light passing through them. Because of the way the light interacts with your filter, this very slightly reduces the sharpness and contrast of your images. It's a barely noticeable and easily corrected effect in Photoshop, but it's there. It's also worse in inexpensive brand name filters. The Hoya, B + W, Zeiss, Canon and Nikon filters had the least impact while brand filters like Tiffen showed the greatest impact.
More seriously, UV filters also make more likely the appearance of stray light or ghosting in your images if you are shooting a scene with a bright light source. In the picture above, you can see some artifacts caused by the UV filter and stray light.
Should you use a UV filter?
Deciding whether or not you should use a UV filter is not a simple question. It really depends. The best advice I can give you is:
- A UV filter will not protect your lens from much more than dust and scratches. If you are shooting at the beach or in the desert, putting one is a good idea, but otherwise you are probably fine without one.
- UV filters have a small effect on the quality of your images. Most of the time, it will not make any difference. But if you absolutely need an image of the highest quality possible, or if your photos show lens glare and other artifacts, you must remove your UV filter.
I would say that there is definitely a place in your camera bag for a UV filter. But it's up to you to decide if keeping it on your camera all the time is worth it. I prefer to remove my UV filters if they affect my images, others prefer to put them on if they turn in a dirty place.
Image credit: Abraksis / Shutterstock