The number of lens filter options (and indeed, knowing whether or not a filter is necessary at all) are at first overwhelming dilemmas that face every photographer. This article aims to simplify what can be an intimidating subject and help readers identify which filter is the best choice to get the job done.
Function
Filters are round pieces of glass or plastic that help achieve effects most film cameras can't achieve on their own. Though many of these effects have been integrated into digital single lens reflex (SLR) settings, nothing beats having full control over how your image turns out. Correctly using filters can often make the difference between a good photo and one that really stands out.
Types
The following are the kinds of filters most commonly used by photographers.
Ultraviolet (UV) Filters: Used to protect the lens glass from damage, reduce haze and absorb UV rays.
Polarizing Filters: Used to reduce glare and haze.
Neutral Density Filters: Used to allow slow shutter speeds in bright daylight.
Graduated Neutral Density Filters: Used when one aperture and ISO setting will result in over- or underexposure in part of the photo.
Warming and Cooling Filters: Warming filters reduce blue tones by bringing out red and orange shades. Cooling filters reduce red and orange tones and bring out blue shades. In digital photography, adjusting the white balance has the same effect.
Effects
The use of lens filters can produce a wide range of effects. Determining which effect you're after will dictate your choice of filters.
UV Filters: Cut through atmospheric haze by reducing the amount of UV rays that get through to the lens.
Polarizing Filters: Typically used for photographing water or glass. They also increase saturation in color photographs, leading to richer tones.
Neutral Density Filters: Usually used to show motion when slow shutter speeds would overexpose the image. These filters are particularly useful when photographing rushing water.
Graduated Neutral Density Filters: These filters are most useful when you are confronted by a situation with two different exposure needs, such as trying to catch detail of both the sky and the ground. Graduated ND filters, which are partly dark and partly clear, allow you to control which portion of the lens receives what amount of light with a single exposure setting.
Warming Filters: Helpful on dark, overcast days or for photos taken in the shade. They are also must-haves to help counteract the bluish cast of snowy scenes and fluorescent lighting.
Cooling Filters: Frequently used to negate the yellow glow of photos taken under incandescent light, or from very sunny outdoor shots.
Considerations
If you have several different sizes of lenses, buy your filters to fit the largest size lens. Then purchase a step adapter ring from any camera supply store; the ring will allow you to use your filter on multiple lenses so you don't have buy identical filters in various sizes.
Warning
The most common problem with filter use is vignetting, in which the edges of the filter overlap the lens and create dark corners on the final image. You can reduce your chance of accidental vignetting by using only one filter at a time, or by opting for more expensive ultra-thin filters.
Dark filters can force you to move one or two stops down to compensate for the filter's light absorption.
Additionally, always inspect your filters for scratches and dirt before use to prevent your photos from being ruined.
Tags: Density Filters, Filters Used, Neutral Density, Neutral Density Filters, Density Filters Used, filters most, filters reduce