For as long as I can remember photographers have either embraced or ignored UV filters for their camera lenses. Most camera stores will suggest a UV filter for each digital camera lens citing protection as the number one benefit. Photographers themselves seem to be divided into two camps. Proponents have them on every lens; opponents don’t even have them in their camera bags. Is there a right or a wrong side to this debate?
Before we discuss any filter it is helpful to understand how the filter will affect your image. Ultraviolet light isn’t within the visible light spectrum for humans. Bees and some birds can see into this color space but it is beyond our abilities. However film and to a lesser extent digital cameras are affected by UV light.
UV light is a shorter wavelength and it is more readily affected by atmospheric “light scatter”. Light scatter causes haziness in a scene, the more the light is scattered the hazier the scene will appear. Since cameras can capture images with some sensitivity to UV light the resulting images can seem to have a distant haze in landscapes for example. By blocking UV light before it enters the camera we can prevent hazy landscape images. This is how the UV filter also came to be known as a Haze filter.
For UV scatter to be a significant problem for photographers the outdoor scene to be captured either needs to possess great depth (think: miles) or it needs to be taken at a high altitude. Outside of these conditions a UV filter will have little measureable affect on an image. So why use a UV filter and not just a plain glass ‘Protection’ filter? The opinion of most photographers is that since both filters sell for the same price the filter you purchase might as well do something, so they go with a UV filter.
The “Pro” side of using a UV filter: A UV filter mounted on a lens protects the front lens element from the world. Not just protection from dirt and grime but impact damage protection as well. Many times each year we are asked to remove a damaged UV filter from the front of camera lenses. If the filter hadn’t been mounted on the lens the front element of the lens would have taken the damage. Better to replace a filter than a lens.
If not properly done, cleaning a lens can cause damage to its coatings. If fine grit isn’t first blown off the glass the lens tissue will cause the grit to grind off the element’s coatings. With a UV filter mounted on the lens the photographer seldom if ever needs to clean the actual front element of the lens itself.
Fingerprints can actually etch themselves into lens coatings over time. Again, would we rather replace a filter or the more expensive lens? Almost every argument for using a UV filter on camera lenses comes down to protection, and that really is the point. Using a UV filter is an insurance policy against damage. Catastrophic damage can still happen, but the every day bumps and dings are less likely put a lens out of commission.
The “Anti-UV” side of the coin: This side of the debate is fully focused on image quality. The argument is that glass filters aren’t made to the same level of quality as the camera’s lens. Filters introduce another opportunity for optical aberrations that can reduce image quality.
While camera lens elements are molded or ground with high precision, some filters are stamped from glass sheets of doubtful quality. To make a high quality filter both surfaces of the glass sheet must be parallel to each other. If the surfaces aren’t parallel distortions are introduced into the image. Think about the last time you looked through the window of a really old house and the world outside looked wavy and distorted. An exaggeration perhaps but it does help visualize the problem.
Other issues that cause concern about using a UV filter are a falloff in both contrast and color fidelity. It is certainly true that low quality filters can allow less light to pass through to the camera’s sensor. In addition some poorly coated filters can have a slight color cast to them.
There are other facets on both sides of this discussion but those mentioned above tend to be the key arguments. There are very real ways in which a UV filter (or any filter for that matter) can protect a camera lens from costly damage. There is an equally real possibility that a filter placed on a lens can indeed degrade image quality. So where does this leave us in our UV filter decision?
In my camera bag I have a UV filter on each lens that I own. The quality arguments against using UV filters I feel can be mitigated by choosing to use the highest quality filters I can afford. I have chosen to use the Promaster Digital HGX filters on my lenses and I have noticed no lack of contrast or color fidelity in my images. Nor do the filters introduce any optical aberrations that I can see under normal viewing conditions. But that is the view from my side of the coin.
A friend who works at one of Porter’s stores wouldn’t dream of putting a UV filter on his lens. He is firmly in the Anti-UV camp for image quality reasons. He has also said that he understands the risk of front element damage his lenses are subject to. The risk in his estimation is lower than the risk of poor quality images. His other point is that the cost of a high quality filter can approach one-third to half the replacement cost of some lenses.
We each have to judge the care we use when handling our cameras. Are we accident prone or do we toss our cameras around in ways that make other photographers cringe? Is there a likelihood that our kids could put a sticky finger into our lens? We have to decide if we can live with possible image quality concerns in order to gain protection for the lens. And now that we have some additional facts it might be easier to make this decision.