I often get asked why photographers / videographers should use CP (Circular Polarizer) filters. Here’s a few reasons why they are a must, especially for landscape photographers:
Before Through CP After
Using a CP Filter:
Increases saturation
Boosts Contrast
Improves Clarity
You can see the dramatic effect of using a CP in the photo examples on the right..
Here’s how they work:
A Circular Polarizer (CP) filter blocks certain light waves reaching the lens which have been directly reflected towards the camera at specific angles. Unlike other filters, a CP involves a certain amount of adjustability and has a rotating ring that you can manually control. This ring, when rotated, blocks specific light waves from entering the lens and subsequently reaching the camera’s sensor.
Given that the angle of light being filtered is important, so is your position to the sun to determine how light will be filtered and the resultant effect on the image. The strength of the effect of the filter (amount of polarization) varies greatly depending on the position of the sun, time of day and season. For example, you can change the angle that is filtered by moving your position in relation to the sun. The strongest polarizing effect is always achieved when you are perpendicular, (90 degrees), to the way that the sun is facing.
Unlike a UV filter, a Circular Polarizer is not totally clear . Instead, it is translucent with a grey-like tone appearance. It blocks certain types of light that are reflected towards your camera at certain angles from reaching the camera’s sensor. By filtering out a specific type of light, a CP filter affects the brightness of the exposure and always darken the overall photograph. This is usually by a reduction of two to three f stops of light. Therefore, certain camera adjustments need to be made to compensate for this loss of light to ensure that your photograph will not be under-exposed. I usually just push up my ISO to offset the slight loss of light once the filter is snapped on or slow down my shutter speed when on a tripod.
BEFORE
WITH CP - CHECK OUT THE DIFFERENCE IN THE SKY AND WATER