Camera Lens Filters: An Introduction
Specialized filters are on the market for many different effects, but I tend to keep them as simple as possible and use only two or three types of filters. Because it goes onto the camera's lens, the quality of the filter will affect the quality of the lens. Stay away from brands you don't recognize and those you think you are getting for a bargain when you find a filter for half the price of the one everyone else buys. Some photographers do not put a filter on their lens because they feel it will adversely affect their image quality. Others always have a filter on the end of their lens to protect the lens from scratches and hits.
Purists say that if you put a $20 filter on the end of an expensive lens, the quality of your lens is lessened. I feel that as long as you buy quality filters you won't lose quality. I have seen plenty of lenses that have been bumped or dropped and were saved by a protective filter. You can make your own choice.
The question then becomes, what filter do you use? Most people think of a UV or Skylight filter, but lenses are already coated for UV protection, so why be redundant? If you add a filter to the end of your lens, why not use one that adds something to your photography.
When using film, I use a warming filter, either an 81 A or B. It is slightly amber and it brings out details, such as in fur and feathers, and cuts through haze you find normally in the atmosphere. An 81 B is slightly stronger than an 81 A.
When shooting digital, the white balance on your camera will compensate for the filter and the filter will no longer give you the warming effect you are looking for. So for digital cameras a less expensive skylight or UV filter is all you need. You can get a warming effect when you process the image on your computer, since photo management programs allow you to create warming effects.
The one filter you definitely want to have with you, whether you use film or digital, is a polarizer filter. These act as sunglasses for your camera lens, as they darken and intensify the blue of the sky and remove glare from reflective objects ,such as water and wet foliage. Even though it is better to create images when the light is at its best, Polarizer filters allow you to shoot in harsh conditions that would normally be unacceptable.
Unlike other filters, you take an active role in the amount of polarization you use by rotating the filter collar on the edge of the lens. There are two mistakes that I often see people make: turning the collar until the darkest image appears in the view-finder and leaving the polarizer filter on the lens all the time. The reason you can turn the filter and determine the degree of polarization is to give you flexibility. Chose the amount of polarization you want, and if you think that less is better, then go with it, you are the photographer. Polarizer filters are at their best when the sun is at about a 90-degree angle to the lens. If the sun is not causing glare or if you don't need to make the blue sky more blue, you don't need a polarizer filter on your lens. At that point all it does is take away light and make you have to increase your exposure or open your aperture. Polarizer filters do not work on cloudy days.