A polarizer's main purpose is to reduce unwanted glare and reflections as well as to increase color saturation in some of the photographs key elements. Polarizers can also darken down a blue sky if used at a 90 degree angle to the sun, but beware of using wide-angle lenses, especially extreme wide-angles as not all of the sky may be polarized across the image. In other words, the sky on one side of the photo may be a deep saturated blue while on the other side it may not show any saturation at all. With digital cameras we can see immediately on the camera's monitor if the polarizer is accomplishing the desired effect that we want.
Compare the pictures below to see the difference a polarizer makes in these two identical compositions taken just moments apart under cloudy skies.
These Photos were taken as camera RAW images and processed in Adobe Photoshop CS5 using identical color balance and adjustment settings for each so an accurate comparison could be made.
Following is the camera's metadata recorded each time the shutter button was depressed, or in this case each time I clicked the electronic cable release button.
|Non-Polarized Image||Polarized Image|
|Date: 10/19/2014||Date: 10/19/2014|
|Time: 8:43:03 am EDT||Time: 8:43:40 am EDT|
|ISO: 200||ISO: 200|
|Focal Length: 24mm||Focal Length: 24mm|
|Exposure Program: Manual||Exposure Program: Manual|
|Aperture: f/16||Aperture: f/16|
|Shutter Speed: 1.6 sec.||Shutter speed: 2.0 sec.|
|Metering Mode: Matrix||Metering Mode: Matrix|
The only difference between the two pictures is that the polarized image required an increase in shutter speed to compensate for the slight loss of light being transmitted to the sensor because of the rotation of the polarizer's front ring.
These images were taken just above Anderson Falls in south-central Indiana using a full-frame Nikon D700 camera mounted on a tripod. Lens used was an AF-S Zoom-Nikkor 24-120mm F/4G ED VR lens with a B+W circular polarizer filter attached.
Last updated or revised on October 28, 2014.
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