Why use a polarizer filters? They are use to eliminate reflections and desaturate color levels caused by glare. They are easy to attach to your camera's lens. The polarizer filter as well as other filters, screw into the threads that are already on the end of your lens. The polarizer filter has an added ring that lets you control what look you are searching for by simply rotating the outer ring on the filter. The benefits of polarizers are most noticeable when photographing blue sky and green foliage. By reducing the glare off of colorful objects with the polarizer filter we can render colors more accurately.
When using the polarizer filter with a blue sky, the filter will darken the blue color of the sky and the white clouds will appear to be popping out from the blue surrounding them. When photographing water, polarizers reduce glare and help bring out the details of the water and what might be seen beneath. The filter may even change the color of the water. They work equally well with eliminating glare coming from windows and other metallic surfaces.
There are two types of polarizer filters, linear and circular. Circular polarizers are used for auto focus and auto exposure systems. Linear are strictly for manual focus and non TTL light metering systems. Circular can be used in manual or auto as well as TTL or non TTL light metering systems.
Remember when using any type of filter, exposure compensation is necessary. Polarizing filters will require 1 to 3 stops exposure compensation. Polarizers can cause a slight vignetting of your image if used with longer or wide angle lens. For the best results try to keep the sun at a 90 degree to the camera and do not shoot directly into the sun.
When shopping for a polarizing filter one thing to remember is optical quality. You do not want to compromise your lens capabilities with a cheaply made filter.The thinner the glass of the filter the higher the image quality. Always screw your filters onto your lens straight on and not at an angle. You do not want to ruin the the threads on your lens.
Polarizer filters can range in price from $25 to $235. As always do your research on the brand and type you wish to buy. Purchasing a more middle range filter around $45 - $60 will be well worth the investment. Remember to check the size of your camera ring first before purchasing.