In which situations should I use my circular polarizing filter?

Question

I received a circular polarizing filter as a gift, but I have a hard time determining when I should be using it.

I've done river shots with some success, but other than that, it doesn't seem to do much beyond reducing the amount of light.

What am I missing?

Answer 1

I use polarizer so much that I never take it off of my main lens. The good thing about it that depending on its rotation you can adjust how strongly it affects you picture from maximum to virtually nothing.

Let's start with what the polarizer physically does:

• it reduces (sometimes completely) the glare from non-metallic objects.

How does it translate to photographic situations?

• enhances the blue of the sky and pulls out the detail on clouds
• enhances the green of leaves and generally colors of plants and their flowers
• makes the water and glass transparent
• reduces the shining of human skin and gives it a soft appearance
• it can remove the rainbow (which I imagine is rarely desired)
• it enhances the overall contrast of the picture, creating very dramatic result in extreme cases

Examples of the same subject non-polarized (left) and polarized (right):

When does it work best?

• when the camera is facing on an angle 90° to the sun and the direction marker is positioned towards sun (hope it's clear - I'm not quite happy with the wording here, will fix it when I come up with something better)

What to be careful about?

• when overused polarizer can give photos a very unnatural appearance (which I personally enjoy)

Answer 2

A polarizing filter removes secondary light, i.e. light that has bounced on a surface and become polarized.

This happens when light bounces off of things like a water surface, glass window, and even in the atmosphere. (Light that bounces off a metal surface doesn't get polarized though.)

If you filter out the light that bounces in the athmospehere, you will get a darker blue sky in your images. When you filter out polarized light in the sky, you get the highest effect if you point the camera 90 degrees away from the sun, and almost no effect if you point the camera towards the sun or away from it.

A circular polarizing filter is used in a SLR camera. As there is a mirror in the camera, the light has to be de-polarized after it has been filtered, or you would not see anything at all in the viewfinder when the filter is turned at certain angles.

Answer 3

Polarizers do block light, as they are designed to filter out light coming from certain directions. Polarizers are useful for a variety of reasons:

1. Mitigating highlights on water, rocks, shiny plant leaves, etc.
2. Enhancing the sky, particularly blue sky, and improving the contrast balance of a scene
3. Bringing out the detail in clouds by reducing their glare

A polarizing filter, particularly circular polarizers, are a great tool to balance out and enhance a scene. They do reduce the rate at which light flows into your lens, so a slight exposure adjustment is usually necessary to compensate. They are generally worth it, if you have one, and can help improve your shots.

Answer 4

Apart from what has already been mentioned (decreasing reflections from water and glass surfaces, bringing out that tourist-brochure blue skies with bright white clouds) it is worth to mention that it also decreases reflections from leaves on plants. Using a polarizer when shooting landscapes with a lot of vegetation helps bringing out a deeper, more lush green tone from the vegetation.

Answer 5

Circular polarizer gives the biggest effect when the light is falling from your left or right and much smaller effect when the light source is before or behind you.

It is most usually used to change color of the sky (lighter/darker) and enhance the clouds, enhance or remove (depending on the position of the filter) reflections off glass or water.