Polarising Filters

Circular Polariser
I am fully aware that I already have a chapter especially devoted to filters, but I have singled out the polarising filter because apart from the UV it’s probably the most widely used filter on the market to date.
There are two types of polariser, the circular and the non-circular. The circular polariser is best for auto-focus type DSLR cameras, but here I will simply refer to it as, “the Polariser”.
The polariser itself is made up of two pieces of glass within a holder that is fitted either by screwing directly onto the filter thread at the end of your lens or slotted onto a filter holder which is also fitted to the lens.
With the polariser fitted, the rear circular glass piece remains stationary, while the front piece is turned to polarise the light that enters the lens and therefore creates the desired effect.
I am not going to go into all the technical side of how the polariser does its job, but it is very interesting and is worth checking it out. Just type the words, “circular polariser” into your browser and see what options you have for reference when you bring it up.
However, there is one technical aspect that I feel you should be aware of, and that is: for optimum best, it must be used at roughly an angle of 90 degrees to that of the sun.
It is not recommended to photograph rainbows with a polariser fitted as it will eliminate some of the reflected colour and possibly lessen the impact of the image.

Its uses:
It is probably best known for its ability to really intensify and enhance saturated colours and make blue skies even bluer; but a point worth noting is, the higher you are above sea level, the darker the sky becomes.
It will cut through haze and is ideal for eliminating reflections on glass, water and most other surfaces that reflect light and therefore ideal for when you are shooting a subject and there are reflected light distractions in the background.
It is worth remembering too, that because it will lessen the amount of light permitted to enter your lens by up to about two stops, there are times when this could be an asset. Especially when a lower light source is required.

For filters in general? Click "HERE"