polarizing filter

Most people use the haze filter just to protect the lens, and leave it on all the time.

I use a polarizing filter on sunny days to darken the sky a bit. That makes the clouds stand out. It also helps prevent sun reflections on surfaces and water.

I try to avoid stacking filters, because it may cause softening of the corners (vignette) if the combined filters stick out too far and mask off the corners.

...
..
.

Polarizing filters are used to reduce reflections and increase color saturation. Typically used when photographing through glass or when trying to capture an image of something floating beneath the surface of a lake or pool.

lense.

Polarizing filters are used to symetric, the scattered reflections from a uneven non-metalic surfaces viz.snowclad mountains,glass panes etc.It also helps to get the clouds from a bright clear sky by darkening the blue.Two types of polarizers are normally available - 1) fixed & 2) rotating.In case of fixed polarizers you have nothing to do,just fit it on the lens,rest will be done by the filter.But in case of rotating polarizers you can control the level of polarization by rotating the front ring of the filter according to your requirements.Actually polarizing filters are made of very small numbers of prisms, which transfers scattered reflections into parallel reflections.When using this filter aparture reduces from 2 to 6 steps depending on the level of of polarization.Another type of polarizer is also available under the category of rotating i.e. circular, which is normally used for AF lenses.