Picture This: Do You Need a Filter?
Filters help protect your lens and enable color correction, but they have drawbacks.
By Earl Nottingham
If you have a camera with interchangeable lenses, there is a good chance that the lens that is on it now has some type of filter attached to it — usually the screw-in type. We use photographic filters for a number of reasons, but their functions are often misunderstood, leading to unnecessary or improper use. Additionally, the transition from film to digital photography changes (and eliminates, in many situations) the need for filters in most shooting situations.
So, do you need to be using a filter? Let’s start with a little background.
Filters can be classified into two broad categories — those for protection and those for correction.
For protection of the delicate (and expensive) front lens element, most camera salesmen will suggest a clear filter such as a UV or slightly tinted “skylight” filter. Those filters produce no or very little color shift in the photograph. It makes more sense to replace a broken or chipped inexpensive filter than an expensive lens if dropped, and it would seem to be a no-brainer to slap a clear filter on every lens in the bag.
Correction filters, on the other hand, are all about changing the color of light being recorded. With traditional film (especially slides), it was common practice to use color correction filters to add warmth or coolness to a scene. Typically, warming (amber) filters such as the No. 81 series or the cooling (blue) No. 80 series were the mainstays of the filter arsenal. Other correction filters compensated for non-daylight light sources such as tungsten (blue filter) or fluorescent (magenta filter). Some filter makers offer creative names such as “Sunset” or “Tobacco” for more intense color modifiers.
Although it is not a color correction filter per se, the popular polarizing filter can also be included. Its unique abilities to remove reflections on shiny surfaces such as water and glass, as well as intensify blue skies and green foliage, make it popular among landscape photographers.
But while filters can be great tools for both protection of lenses and correction of the color aesthetics of a photo, they come with several downsides that raise the question — “Should I really be using a filter?”
Regardless of the type of filter used (but especially for cheap UV filters), two issues arise that have the potential to degrade the quality of a photo. First, any filter placed in front of a lens will degrade the image to some degree. After all, you are putting an inexpensive piece of glass in front of a well-designed optical instrument. The effects are often not noticeable, but filters can degrade sharpness and induce color aberrations, primarily around the edge of the image. Second, any filter sitting atop a lens (especially a dirty one) is susceptible to lens flare, especially when shooting in the general direction of the sun without a lens shade. The effect you see is much like driving a car with a dirty windshield toward the sunset — not good. Unless I am shooting in a very dusty or sandy environment, I rarely use a protection filter, opting to replace the plastic lens cap when done.
A lens shade provides needed protection if the camera is dropped and is designed to soften impacts and break away before damage is done to the lens. (If you don’t have a lens shade, a good practice is to use your hand or a cap to shade the lens from the sun.)
With digital cameras, color correction filters have pretty much become a thing of the past because the camera can automatically correct the color cast from differing light sources. Many of the saturated sky and foliage colors previously provided by the polarizer filter can be achieved with the “Vivid” or “Landscape” color profiles found in most cameras or by the camera’s HDR feature. The polarizer is still the go-to filter for controlling reflections.
Filters do have their place when used judiciously, but be aware of their limitations and potential for ruining an otherwise great photo.
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