Tuesday, April 8, 2014
Gadget Bag: Polarizing Filters
For landscape photographers, a polarizer is a must-have accessory you should carry at all times. It does much more than simply darken the sky.
The term "filter" has become ubiquitous, as the ability to transform the color palette, texture and grain of an image now can be done with one touch using a Photoshop plug-in or an iPhone app. While we can take advantage of this technology by personalizing and perfecting postprocess filters, devoted nature photographers know that not all filter effects can be re-created in the computer accurately. In particular, the special look created by a polarizer only can be achieved by shooting with the physical glass filter attached to your lens.
When light is reflected from nonmetallic surfaces in nature, it becomes polarized. This is seen in the glare of water reflections, wet surfaces from dewy mornings and details lost on overcast days. Additionally, the sky experiences polarization from scattered sunlight, creating lighter, washed-out blues. Cameras don't record polarized light information, so it's impossible to change specific polarization in post, making it important to do desired adjustments in the field.
Similarly, a polarizer adds saturation to a sky. The placement of the saturation is dependent on the location of the sun, as well as where you situate yourself. The sky is most affected by the polarizer at a 90° angle from the direction of sunlight, so if the sun is overhead, the sky near the horizon has more depth. Playing around with timing provides experience for previsualization. Another fun moment to pull out the polarizer is for rainbows, as the filter can enhance (or remove) colors.
One important note: When using a polarizer, you often lose 1 to 2 stops, so you need to compensate when you add it to your lens. Because of this, you also may prefer to use the polarizer when you're capturing still scenes or using slow shutter speeds as opposed to quick wildlife shots.
In the world of polarizers, there are many options with different types of mounts, coatings and even additional color blends.
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