I am going to start this blog by stating that I own a protective glass filter for every lens I own. They are not UV filters or Skylight Filters. They are clear glass filters and I suppose they have some sort of multi coating. I only use the best filters made and they are usually Heliopan, B+W, Carl Zeiss, and Fuji. These are not cheap filters. They cost anywhere from $60.00 to $120.00 depending upon the size and make.
What does a UV filter do?
A UV filter helps to eliminate blue casts caused by UV Rays WHEN USING
FILM. Digital cameras use sensors and UV correction is no longer really necessary.
A Skylight filter has a slight
warming effect on an image.
There are two schools of thought when it comes to screwing a protective filter on to your lens.
School number 1
People who are part of this school believe that the protective filter Is essential for protecting the front element of the lens under all Conditions.
They also feel that they would rather clean a filter instead of the front of a lens because there is less chance of scratching the front element should there be some kind of grit on it.
But the main reason is protection as the name implies. Protection flying stuff, bangs and dings, hurricanes and drops. I have a cat that finds great joy rolling camera stuff of the dining room table where she and my camera equipment have no right to be.
School number 2
Folks in this school feel that putting a protective type of filter on the front of a lens is kin to putting a couple of layers of Saran Wrap on the front of the lens. They feel that image quality is impacted edge to edge of the given frame.
They feel that the extra glass surfaces will cause flare and under certain conditions produce an effect called ghosting. Ghosting could occur at night while taking a picture with street lights in it and up against a dark sky or building, more so when the lens is wide opened.
Vignette. This is the shading of the of the image, which could be caused by the mount of the protective filter, adding just enough front end extension to block light. This usually looks like the corners are about a stop darker than the rest of the image.
Going off on a bit of a tangent, there are those in school number 2 who believe that a lens hood serves the purpose of protection. Speaking from experience, a lens hood does add an extra layer of protection and it does so without adding another glass surface.
Lens hoods are essential for every lens and you should not leave home without it. Simply it prevents flare and even more important it prevents light from above the sides and below from hitting the front element and causing a drop in contrast. LENS HOODS ARE ESSENTIALOR EVERY SERIOUS PHOTOGRAPHER.
Okay I am back from the tangent.
So who is right and who is wrong and is there a middle ground?
There can be middle ground and the middle will be different for everyone.
Points to make
I have not experienced a measurable loss of image quality by using a filter but I also use very good filters.
I have experienced ghosting as described above
I have had some vignette issues on ultra wide lenses but that can happen even without a filter
I have had a filter shatter when it was hit by a flying rock from the road. The front element survived and it may not have had the filter not been on the lens.
What do I do? Like I said above when this blog first started, I have a protective filter for every lens I own. I only use them under what I consider to be adverse conditions.
Those conditions are:
Being on beaches with blowing sand or salt water.
Polluted smoke areas with possible debris in the air
Muddy forest trails, and the like could require protection
Rainy and misty conditions. Safer to wipe of a filter as opposed to a front element.
So I keep protective filters handy if I feel I need them, but do not keep them permanently on a lens.
Lens hoods. They are always on my lenses. Period. If you do not then you should expect image degradation caused by extraneous light. They can also serve to protect the front of lens. As an example, misjudging the width of a doorway where suddenly you plus your camera and lens can’t all fit and your camera bounces off the door jam.
I also carry filters that do have overall impact on images.
Variable Neutral Density
I have one each of these filters. They accommodate my largest lens. If I need these filters for smaller lenses then I use adapter rings so the larger filter fits on to a smaller lens front. As an example a ring that goes from 58mm to 72mm.
If you are concerned about the image quality being impacted then make sure you buy the best filters. Again, Heliopan, B+W, Fuji, Carl Zeiss. They should be neutrally clear. There is no need for them to be UV correcting filters. Just clear optical glass.