When we think of UV, we think of sunscreen and ultraviolet rays. When it comes to photography, the thought of a UV filter is to protect the lens. But, what else does it do? To better answer this, it's important to understand more clearly what UV light is. The visible light spectrum runs from red to violet. Red light has the longest wavelength and violet light has the shortest. Light with a longer wavelength than red is called infrared, and light with a shorter wavelength than violet is called ultra violet or UV.
UV or Not to UV?
Upside: The fact is, today most DSLR sensors aren't affected by UV rays, and so the filter's primary role is as a protective filter. Back in the days of film cameras, UV protection was needed, but we've come a long way since then. For a DSLR a UV filter and a protector filter are the same thing. Much like our smartphones have protective cases, we want our camera lenses to be protected and the UV filter is just the ticket for doing so. It protects the lens against kids' greasy little hands that love to touch things. Dogs nose prints. And, for those who live in places where the elements of sand, sea salt, and dirt are an issue, it's a protective layer against Mother Nature.
From some photographers' standpoint, the UV filter takes away from lens flare and unwanted reflections (though not to the same level as a polarizer). Others are clumsy and even with their camera strap have the tendency to drop things or accidently bump their cameras into things that might scratch the lens. It lessens the need to use a lens cap consistently during a shoot. And, of course, it's easier and less worrying to clean the filter than the camera lens.
Downside: When you use a filter, UV, polarizer or any other filter a new optical layer is added where light can be reflected and refracted. If you're out shooting at night or if you are shooting from in front of your light source, the filter can cause unwanted flares, which reduces the quality of your shot. This holds true for any filter, not only UV filters.
There is the possibility that the UV filter will also cut down on sharpness. This might be something you want to experiment with. Try taking a particular shot with and without your UV filter and see if it makes a difference. If so, that's a consideration. If the elements, like sand, dirt, salt, aren't an issue - like if you're in a park doing a portrait shoot - then it may be worth removing the filter.
Tricks of the Trade
Naturally if your lens might get dirty, then so can the filter. I recommend keeping a few filters on hand so if you're shooting at the beach and spray gets on one, you can change it out without having to mess around with trying to clean and remove the smudges.
Some photographers couple a polarizer filter and on top of the UV filter. The reasons I don't suggest doing this is that you increase your chances of vignetting, especially with wide angle lenses. There's no need to, so take the UV filter off when adding other filters.
A lens hood coupled with your filters will also help cut sun glare and to protect your lens. They're worth the investment of money and usage.
As with most things, quality comes with a price and UV filters are no different. No matter what, they're cheaper than replacing a lens! UV filters are not created equal. Some of them are made of a thin piece of inexpensive glass, while others are made with a thicker, better quality glass and have multiple coatings for increased sharpness and performance.
To help you do your homework, check Amazon most popular UV filters currently on the market, ranging from cheaper Tiffen UV’s to the more expensive Hoya UV’s. If your budget allows for it, and if you think you'll use the filter frequently, spend the extra bit of cash and don't look back.
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