Filters for Protection, Polarization, Infrared and Ultraviolet
Related: filters, infrared, polarizer, spectral transmission, ultraviolet
Filters have a variety of uses, many of which have lessened with the advent of digital camera white balance. But that doesn’t mean just any filter will do.
See the Buying Tips page.
Which type of filters?
There are only two types of filters for regular use:
- a neutral filter for lens protection (eg a “UV” or “clear” filter);
- a polarizer for reducing reflections and atmospheric haze.
A warming filter is not needed with a digital camera, since the white balance can be adjusted in the camera. Even strongly blue scenes do just fine, according to my research.
If you’re shooting a high grade lens, a quality filter usually won’t hurt, but it won’t help, unless it’s a polarizer and the goal is to cut glare, or some other particular reason, like perfect color balance.
If you’re using a filter for lens protection, don’t skimp and get a cheap filter, because even the very best filters can degrade image quality. And keep the filter spotless if you’re shooting into bright lighting.
If you have an inexpensive lens, why bother? A good quality filter can cost half as much as some basic lenses! The exception would be a cheap filter for salt spray or blowing sand, etc.
See the Schneider B+W filter handbook.
A polarizer is the only filter that can remove glare, or darken the sky. It can also reduce atmospheric blue haze to a limited extend, depending on the nature of the haze.
With the sky, peak polarization is at 90° from the sun, declining to 0° at 180° from the sun. For this reason, the effect can be “banding” in the sky with wide angle lenses 24mm and wider— it looks wrong, so use care.
I use a polarizer rarely, because the effect is frequently too postcard-like for my taste, a cliché I try to avoid. Use a polarizer judiciously, and remember that removing glare can make a scene look very unnatural, and can also make water look great, or fake.
Infrared and ultraviolet photography
Spectral transmission measurements
Spectral transmission graphs on subsequent pages were measured by Coastal Optical Systems on specialty optical equipment using single samples of the specified filters. Graphs used by permission.