This UV filter has sacrificed itself to save the much more expensive lens
If you want to see a room full pleasant, professional photographers get into a brawl, ask them about UV filters for a digital camera’s lens. Aside from Nikon vs. Canon debates, whether you should or shouldn’t use a UV filter is quite a contentious subject. Some photographers will be adamantly against UV filters, some completely for them, some neither one way or the other. Rather than get a pack of piqued photographers together, I will try to give a comprehensive overview of the pros and cons of using a UV filter on your lens. Note: If you get bored with all the technical stuff, skip to the last paragraph for the best bits.
The UV you don’t see
There are UV filters out there in abundance. There’s filters that go by names like “skylight” or “haze.” In addition there are UV-A and UV-B and “Universal UV” filters to make matters even more confusing. For the most part, they are designed to block UV (ultraviolet) light from the camera lens in outdoor situations.
UV light is a part of the spectrum we can’t see, so we can’t judge the effect it may have on our pictures. In film cameras, the film is sensitive to UV, so the UV light can affect how the picture looks without us knowing it. Contrast can be flattened, glare may show up making a picture appear washed out and at times blueish. Using a UV filter eliminates the offending light and saves the film image.
But what about digital cameras and sensors? Digital cameras are not very sensitive to UV light, therefore UV light will have little or no effect on a digital image. That wishy-washy, less-contrasty, bluish image you may get in film is nearly completely absent from a digital camera without any need for a UV filter. So, then, why do you need a UV filter at all?
The nitty gritty: Protection!
Well, the answer to the question above is: You don’t. However, there may be things other than UV light that can hurt your image, and, possibly, your lens. Just before going out on a photographic jaunt, you’ve checked the front of your lens and it’s spotless and you’re ready to go. Unfortunately, the outside world conspires to make your lens dirty. Depending on your environment and subject, your lens glass can suffer from dust, water spray, even dog noses and children’s fingers.
Take a look at the front of your lens. It’s curved. Some of them are quite curved. It has a spot where the glass lens and the metal lens housing meet. Look closely. Although you may not see it, there is likely a very tiny gap. See anything? I hope not. Getting junk in there such as dust, dirt, grime and water would be troublesome and might require a trip to the camera repair shop.
In the instance of digital cameras, rather than keep UV light out, the filter serves to protect the front element of the lens from all that nastiness and reduces the need to clean the lens. (Really, you shouldn’t need to clean your lens too often, and even then, be gentle. I’ve seen cases of overzealous cleaning having caused more troubles than any direct physical damage.) This is the true nub of getting a UV filter, to protect your lens investment from nasty mishaps, dirt and water. Has that already happened to your lens? Look closer. Is that a smudge? So the idea is you clean your lens spotlessly (I have another article about how to clean your lens) and be sure the filter is spotless, then pop that filter on there and you are good to go. While out shooting, if you encounter less than ideal elements, your lens won’t suffer the brunt of the insult, and a lens filter is far easier to clean or replace than the lens it’s mounted to.
Another often-overlooked aspect the filter protects is the threads it screws into. This rather exposed part of the lens can be damaged by drops or a sharp whack against a door jamb, or in my own case, a stick being wielded by a mad 8 year old. Bending, denting or distorting the threads renders them useless for attaching other filters and even the lens cap. Usually this results in lens replacement, or at the very least, a much less useful lens. Again, the filter protects this area by the very fact it’s standing guard, being the first line of defense on your camera.
The picture at the top of the article shows a lens that got hit by a rock while shooting a rally race. In most circumstances you probably won’t encounter that kind of situation, and whether a simple filter will protect your lens is anybody’s guess. But, hey, maybe it will help. The filter saved at the very least, a bent filter ring and a nasty scratch. At the very worst, it may have prevented an expensive lens repair.
All-in-all, unless you do anything other than shoot pictures of hermetically-sealed stuffed bunnies in a clean room lined with rubber, there is a likelihood that your lens will suffer some sort of indignity. A filter can keep the gunk off of the front of your lens and give you a bit of peace of mind.
What’s the bad news?
There are a few things to be aware of while using a filter, but with some understanding filters are still good to use.
Because it’s something in front of the lens, the amount of light that gets in will be reduced, if ever so slightly. Even the clearest piece of crystal would reduce the amount of light entering the lens, so it’s to be expected. Fortunately, with a good filter it’s a very small amount and for the most part it will be unnoticeable. Now, notice I said a “good” filter. Quality is important.
If you get a UV filter, get one that has a neutral cast. They usually don’t say “UV-A” or 
“UV-B.” Better yet, look for filters that are specifically made for digital cameras. Usually they are just called “protection” filters and are completely clear.
Lastly, be very aware that not all filters are not created equal. Lower quality filters may reduce image quality by creating color shifts, decrease contrast and even causing distortion, essentially exactly creating the effects they were designed to eliminate. So that $5-on-sale filter you got of cheepcamerastuff.com (not a real Web site) may not be the bargain you bargained for. Read the reviews and do a bit of research, but most of the good filters cost about $30 or more. There are many makes of filters available, but the most popular are Tiffen, Hoya Pro and B+W. These are proven names and have delivered consistent results overall. Purchase one through a trusted retailer and test it out by taking the same picture with the filter on and with the filter off. Do this with a few pictures. If doesn’t provide good results (in other words, not change your image at all) return it and try a different brand or model.
When NOT to use a UV filter
There are specific instances you really should not use your UV filter. Though many photographers see it as a “fit and forget” piece of equipment, there can be some drawback to the filter, even if it’s a really good filter. Night and flash photography. with a UV filter can cause additional glare and ghosting on your image, again, because it’s simply another piece of glass. Using one while indoors can cause a sort of overall glare, which will wash out the image overall.
The last word
Do you need a UV filter for the front of your lens? Truthfully, a UV filter is not a necessity. Your lens is designed to work just fine without one and give you great results. But in certain conditions something protecting your lens may be a good idea. A dusty environment, splashes and dampness can all wreak havoc with your costly lens investment. In these situations some sort of protection may help avoid cleaning, repairing, or in a worst case scenario, replacing your lens. If you do decide to get either a UV filter or a clear lens protector, get a quality product that won’t affect your image or your ability to capture it. You won’t need to use it all the time, just the times you think it would be wise to protect your lens.
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