A photographer friend and I were talking recently about how and why we use filters on the lenses of our cameras. The discussion centered around clear “lens protector” filters, but in that same group of filters are “UV haze” filters, and “skylight” filters.

They all do essentially the same thing to your images: nothing. Many photographers use them to keep rain, smoke, dust, and their own clumsy finger off the front elements of their lenses.
In the film era, the thinking was that ultraviolet light in the atmosphere would be a problem because it would contaminate our images. The answer was the UV (ultra-violet) filter, sometimes with the word “haze” added because it would supposedly reduce the appearance of haze in the distance, since haze tends to be in the blue to ultra-violet portion of the spectrum. If you look closely, you will see this filter is very faintly yellow.

Likewise, a lot of film photographers, including me, used a “skylight” filter on their lenses, since magazines like Modern Photography and Popular Photography told us to. This filter appears very faintly pink if you look through it.
Those filters were intended for use primarily for color photography, but we almost always left them on our lenses when we shot in black-and-white. The exposure penalty is negligible, as is any noticeable tonal rendition.
Other filters for color film photography included color correction filters for use with daylight-balanced film in incandescent or fluorescent light, or to fine-tune color balance in a studio setting.

A popular filter paradigm in the late-1970s was the “graduated neutral density filter,” so named because they gradually got lighter or darker across the image area. You could get these filters in colors, too, so your image would be unchanged at the bottom of a frame, for example, and blue or brown or red toward the top of the frame. Watch the intro the the movie Top Gun, the jets on the carrier scenes, and you will see that they used exactly that to created those sunsetty-looking shots.

Like a lot of trends, this kind of filter system experienced a flash of popularity which waned quickly, but stuck around at a low level, and once in a while you can see these filters in use, especially with nature photographers.

My favorite kinds of photographic filters are for black-and-white photography, although I didn’t get to use them very often. Their impacts on images could be dramatic. Red and orange filters would block blues and greens, creating deep, dark skies and cutting haze, while yellow and green filters tended to help black-and-white films respond more realistically. Blue filters, thought seldom used, darkened red and yellow areas, and lightened blues.


Finally, there are polarizers, but I promise to cover those in another article.
The golden age of filters is gone, mostly because of editing software like Photoshop, which can accomplish most types of filtration effortlessly.
