Filter Guide: What is a UV Filter, and Do You Really Need One?
Almost everything in digital photography stems from film, but sometimes, there are film traditions that create quite a stir. UV filters are just one of those traditions that’s creating a divide between photographers. Some will insist you need them and others are adamant that image quality suffers as a result of using one.
So, who’s right? And what exactly does a UV filter do? Here’s what you need to know about UV filters.
What is a UV Filter?
UV filters block out UV light. With a film camera, UV light in bright outdoor conditions often created a bluish haze to the image. Digital sensors, however, and rather insensitive to UV light, so there’s no blue haze when shooting outdoors, even without a UV filter.
But since digital sensors don’t mind one way or another, UV filters have become popular instead as an option for protecting the front of the lens. Sure, a filter won’t protect your lens if you drop it, but adding an extra layer prevents the lens from being scratched. A scratched UV filter is much cheaper to replace than a scratched lens.
Since the digital sensor is insensitive to UV light anyways, leaving a UV filter on the front of the lens doesn’t affect the exposure at all. And that’s where the use of a UV filter for protection comes from—but it’s a hot topic in the photography community.
The Argument For Using a UV Filter
Since UV filters are much cheaper to replace, they’re most often used to protect the lens from scratches. Even if you’re not a klutz, sand blown by the wind isn’t good for the lens front either.
UV filters are also easier to clean. Fingerprint smudges are easily wiped off. A UV filter will also keep the rain from the front of the lens, or salty sea spray, or mud kicked up from a dirt racetrack…you get the picture. If it’s on the UV filter, at least it’s not on the lens front.
All of this protection comes from a filter that doesn’t affect exposure, so it can be left on inside and out, unlike, say, a polariser that works great outdoors but can mean using an even slower shutter speed indoors.
UV Filters are also relatively inexpensive. Some options are available for under $10, while other thicker options with more coatings are closer to $50.
The Argument Against Using a UV Filter
While the UV filter doesn’t affect exposure, that doesn’t mean it doesn’t affect the image at all. The more pieces a lens has, the more prone it is to lens flares—though whether or not one more piece really makes a difference is still debatable. Those who opt to use UV filters argue they can always take them off if they notice flaring.
But additional ghosting on the image has actually been demonstrated on shots taken with and without the filter. When this does it occur, it’s usually at wide open apertures, when light reflects off the filter, creating a glowing orb of light where there actually isn’t any light in the image. These occasions are pretty rare, however, since it’s usually a very bright light on a dark background and is even more pronounced when overexposed.
There doesn’t appear to be any other difference in image quality, such as resolution and exposure.
UV filters also shouldn’t be left on when using another filter. While many of them include threading, making it possible to stack filters, this can create a vignetting, especially at wide angles. That just adds one more step to remove the UV filter in order to use a different one.
A lens hood also offers a bit of protection, which may make a UV filter unnecessary. The filter also doesn’t protect the lens from drops, just scratches and dust to the front.
While UV filters are relatively inexpensive, photographers against their use for digital cameras say it’s just another piece of equipment to buy and carry that you don’t really need.
So, who should get a UV filter?
Whether or not you use a UV filter is a personal choice, however, there are a few types of photography where the protection of the UV filter comes in handy.
- You probably don’t need a UV filter if you do most of your shooting inside a studio.
- A UV filter is a good idea for shooting in areas with a lot of sand, including dessert regions and beaches.
- A UV filter can be helpful when shooting in the rain, though you should certainly take additional measures to keep your gear dry as well.
- If you photograph children, fingerprint smudges are easier to wipe off of a UV filter than off a lens.
- If you invest in expensive lenses, you may want to protect against scratches with a UV filter.
- If you often shoot in scenarios that create ghosting, with bright lights on a dark background, you may not want a UV filter, or you may want to remove it for these shots.
What UV Filter Should You Buy?
If you’ve weighed the pros and cons of using a UV filter and have decided it’s the right fit for you, then what?
While a UV filter doesn’t affect image quality most of the time, that doesn’t mean you should just pick up the cheapest one that will fit your lens (the measurement you need for your lens is usually written on the inside of the lens cap). The best UV filters will be a bit thicker, and have additional coatings to prevent ghosting. Cheap filters without enough clearance can actually ruin lenses that have a slight curve by getting too close and scratching the lens.
Look for a UV filter from a reputable brand, such as B+W, Tiffen or Hoya. B+W is one of the best options for UV, though a bit more expensive, they are better built and will offer more of that protection.
Thanks to the design of digital sensors, a UV filter isn’t a necessary piece of equipment. But, the filter can make shooting a bit easier by preventing scratches to the front of the lens, as well as making clean-up easier.