UV filters as protection on a lens. This subject has been a huge constant battle among photographers for as long as I can remember. The topics range from quality of glass, protection, vingnetting, and more.
Right off the top, I DO NOT use a UV filter on the front of any of my lenses. I will do my best to give information in this article on both sides of the issue so you can make your own informed decision instead of going with the cool crowd.
UV or Skylight filters ( I’ll just say UV from this point forward) are traditionally put in on the front of your lens to protect it from being scratched. While this is a good theory it has quite a few drawbacks.
First, lets examine the construction of the filter. Basicly the UV filter is a piece of glass coated to keep the ultra violet rays of the sun from hitting the film. Today film is rare so this factor isn’t really an issue.
The glass is surrouned by a metal ring which screws onto the front of the lens. Here is the first problem. If you have a wide angle lens sometimes this filter ring will be seen at extreme wide angles and cause vignetting. There are some filters that are “slim” design which have a thinner ring construction but most of those do not have theads on the outside to put a polarizer or any other type of filter you may want to attach. So there is problem one; vignetting caused by the filter ring.
Another problem is the quality of the glass used to make the filter. Lens manufacturers spend a fortune to test and develop and polish their glass to perfection for the lens. Then you just slap a cheap filter in front of all that expensive polished glass. This will create a noticeable difference in image quality. I can say with certainty that filter glass is not the same quality as lens glass. So there is problem two, lower quality of glass in front of optimal quality lens glass.
In the following pictures you can see the difference between pictures, one with a filter and one without a filter.
with filter above
without filter below
An additional problem is that today’s cameras are all basicly handheld computers. They are calibrated for use without filters. When you put a filter in front of a lens it changes how the camera reads the image and can cause subtle exposure and color changes as it reaches the sensor. There is problem three, changes to the image exposure and color.
Now, there is the advantage of using a filter to protect your expensive lens. If you have a filter in place and you hit the front of the glass it will damage the filter but hopefully not the lens. Also this can work for banging the side of the filter ring. You will again damage the inexpensive filter instead of the main filter rings on your lens. I see these things as irrelevant.
Firstly, if you respect your equipment the risk of damage to the lens is much lower. I use lens caps, and lens hoods. Both of these together have worked great for me, I have never scratched the glass on my lens or dinged the filter ring either. I have often hit the end of the lens hood so I definitely recommend leaving that in place. Usually when I’m driving around doing my landscape and wildlife work I have cameras sitting on the passenger seat of the car. I have had them fall off the seat, accidents happen. But even with them falling off the seat to the floor the lens hood protects the end of the lens from breaking and the lens cap prevents scratches. I think that if I only used a UV filter I would have more severe damage.
Using a filter is a personal decision, you have to judge in your head what kind of a risk you feel is acceptable. I personally feel that anything in front of the lens that can degrade the image is a liability. Image quality comes first to me. Whatever you chose just try not to drop the camera in the lake, no filter will save that. Ha ha ha