ESSENTIAL FILTERS
Good quality filters are expensive.
The digital photographer needs at least two kinds of filters - a polarizer and a grey graduated.
The photographer needs a set of at least two grey graduated filters, although having a variety of densities is better - .6 and a .9 density. The main purpose of this filter is to reduce the brightness of the sky. They are neutral in colour and their only purpose is to absorb light.
A polarizing filter can have a dramatic effect and can be used in any lighting conditions. This does not mean that it must be used every time.
When using this filter there is a loss of light of about two stops. Through the lens metering will automatically allow for this, otherwise the photographer needs to compute this value into the exposure calculation.
A polarizing filter removes reflections, (it will not remove reflections from metal surfaces.) It can increase the sky contrast making it a deep blue, the effect is more pronounced when the sun is to one side of the camera - ( Figs 1 )
There is one possible disadvantage in the use of the polarizer - it is that it has a darkening effect on the shadows. If the photographer keeps this in mind, he can make this apparent negative into a positive by using this filter to darken shadows when they need darkening.
