Filters are made of glass, plastic and gelatin. Glass filter are more expensive, but have the advantage of lasting longer and of being more resistant to scratches and damage. They screw onto the front of your lens easily and quickly. When buying a filter take your camera with you to be sure that you get the correct size to fit your lens.
At this stage of your photographic life there are two filter which will be helpful:-
The skylight filter
The sky filter absorbs some ultra violet light (ultra violet light, especially in pictures taken in mountainous areas, produces a blue haze in the distance). The skylight filter is pale pink in color and this helps to correct the blue cast which occurs in shady areas when the sky is blue.
It is particularly useful when taking pictures of people under these conditions. This filter will not reduce blue haze at sea level, only at high altitudes.
As this filter is so pale it has no effect on exposure and can be left on your camera lens, which protects the lens from dust and damage. However, do make sure that the filter is clean and free from dust and finger prints.
The polarizing filter
The polarizing filter acts in the same way as polarizing filter acts in the sane way as Polaroid sunglasses. It is much more expensive filter than the skylight, but is one of the most useful filters you can buy (or put on your Christmas present list). The glass is tinted grey and it rotates in the mount.
This filter reduces reflections in windows, water and non-metallic surfaces, but only if you take your photograph at an angle to the reflecting surface. It also reduces mist and haze. It darkens blue skies and has the effect of making colors appear brighter and clouds whiter.
Rotate the filter until the best result can be seen. The polarizing filter has no effect on dull days, or sunrises and sunsets.
An instruction leaflet will be closed with the filter. Read it carefully. You will see hat you need to give an extra 1.5 or 2 stops exposure when using it, e.g. if your exposure reading without the filter is f11 at 1/125th second, then with the filter it should e f5.6 at 1/125th second or f8 at 1/60th second. Cameras with through the lens (TTL) exposure metering will automatically do this for you.