Polarizing filters are a magical thing! With the advent of digital photography and computerized post-processing, software is now able to recreate many of the effects that creative filters were used for in the past. However, polarizers are one of the few types of filters whose effects cannot be recreated in post-processing. Polarizers change the light coming into the camera and can do some pretty amazing things!
The most common use of polarizing filters is to remove glare from water allowing you not only to see below the surface of the water, but to enhance the overall color of images containing water. But this is far from all that a polarizer can do for you!
Purchasing a polarizing filter:
The first thing you want to make sure of is that you purchase a circular polarizer (sometimes referred to as CPol) if you are just newly stepping into the world of polarizers, as opposed to a linear polarizer. Linear polarizers will cause your in-camera light meter to be unreliable and maybe even unusable. The good news is that circular polarizers are easy to find!
As with most things photography related, you get what you pay for. Polarizers consist of more layers than a typical UV or color filter, and as a result, they are more complicated to manufacture and therefore more expensive than other types of filters. It is important that every layer be of a good quality, otherwise the filter will degrade the quality of the final image. Expect to spend a minimum of $100 on a good quality circular polarizer. (B+W and Heliopan are great brands!)
As with all filters, the size of filter that you buy is based on the filter thread of the lens you are using. However, if you would like to be able to buy just one polarizer and be able to use it on all your lenses, here’s a money-saving trick. Buy your polarizer in the largest filter diameter of all your lenses (or even bigger if lenses with larger filter threads are on your wish list). Then, buy stepping rings so that you can attach the polarizer to your lenses with smaller thread diameters.
I have a 72mm polarizer, but my current lenses have 62mm and 52mm threads. I also have a 72mm to 62mm stepping ring and a 62mm to 52mm stepping ring. I use either one or both of the stepping rings depending on the lens that I am attaching the filter to. Stepping rings cost under $20, so a couple of those are far cheaper than buying a separate polarizer for each lens.
How to use a polarizer:
Start off, of course, by attaching the filter to your lens. While looking through the viewfinder, rotate the outside edge of the polarizer. You will see the colors and saturations change as you rotate the filter. When you achieve the desired effect, shoot away! As you rotate the filter through 360°, it will go all the way from minimum effect, to maximum effect, and back to minimum affect TWICE! Or to put it another way, it only takes a 90° rotation to go from minimum effect to maximum effect. Why does this matter? Well, if you’re shooting in landscape orientation and you have rotated your filter for the desired effect and then switch to portrait orientation (rotating the camera 90° in the process), you’re going to completely chance the polarization effect. Every time you change the orientation of you camera, you have to re-adjust your filter.
Polarizers are most effective when shooting at a 90° angle to the sun. So if the sun is directly to your left or right, you are going to see the most dramatic differences as you rotate the filter. If the sun is directly in front of you or directly behind you, you may not see much difference at all.
When to use a polarizer (and when not to use one):
If you want to remove glare from water to take photos of what’s below the surface, this is where a polarizer is really irreplaceable! Here is a photo taken both with and without a polarizer. I promise, there really were dolphins under the surface of the water in both photos, but the glare from the surface of the water meant that without a polarizer I was never going to be able to photograph them.
Polarizers are also great at boosting the overall saturation of an image and can make pretty blue skies even bluer, giving an image with more tonal contrast.
As I mentioned above, polarizers are most effective when shooting at a 90° angle to the sun. This is something that you want to be mindful of when shooting with wide angle lenses. When using a 24mm lens on a full frame camera, you will have an approximately 84° angle of view. This means that one edge of the frame could have the full effect of polarization, while the opposite edge of the frame could have next to nothing. This can result in some pretty crazy and unappealing gradiations in the color of the sky.
Polarizers are like putting sunglasses on your camera. Depending on your exact filter, they can end up giving you 1-2 stops less light. If you are already shooting at the low light limits of your camera, it may be better to forego the polarizing benefits in exchange for the additional light you can get into your camera by removing the polarizing filter.
And one of my favorite little secrets…rainbows have polarized light in them! When shooting a rainbow with a polarizing filter, it will make the colors more vibrant resulting in an almost magical quality that will have you wanting to search for the pot of gold!
If you have never tried shooting with a polarizer before, I’d highly encourage you to give it a try. It can bring a new level to the natural color and contrast of outdoor photos, and it can open up a whole new world of possibilities when taking photos that include water and glass by allowing you to take control of the reflections that you are presented with.