Filters are sheets of plastic, optical resin, or glass that, when added to the front of a camera lens, adjust the light passing through the lens. How the light is adjusted depends on the filter. ◾ Some types of filters add color to the light and thus add color to the final photo. Warm-up filters, for example, add yellow-orange to a shot. ◾ Other types of filters can be used to reduce the amount of light entering the camera. These filters are known as Neutral Density (ND) filters. ◾ Filters are bought in one of two forms: screw-in or filter holder.

SCREW-IN Circular filters that attach directly to the filter thread of a lens.  Advantages • Good range of types readily available • Inexpensive Disadvantages • Often need to buy multiple filters if you have more than one lens

FILTER HOLDER Square filters slot into a filter holder that is attached via an adapter to a lens.Advantages • Can be used on multiple lenses by attaching adapters to the lenses Disadvantages • Initially expensive • You get locked into one manufacturer’s filter system