Let’s explore polarising filters—watch the above video for a live footage guide of how to use them, including caveats to be aware of when shooting.
By polarising the light entering the lens, we can achieve a range of effects, including:
- Increased saturation, especially with blues, greens and yellows.
- Darkening and deepening sky colours.
- Cutting through atmospheric haze.
- Reducing or neutralising reflections—great for water shots, motorsports (e.g. seeing a driver through a car windscreen), architectural shots with lots of windows.
- Bear in mind the light loss of using a polariser—a typical polariser eats up a stop of light, so you’ll need to expose accordingly.
- Circular polarisers, whilst ideal for modern digital cameras, can also cause a ‘black spot’ effect when used with wide angle lenses. This becomes even more problematic if you’re shooting panoramas with wide angle lenses. You may see a circular vignetting effect that is difficult to retouch.
- Polarisers will also influence white balance, and it may throw off the camera’s auto white balancing if you’re using it. Expensive polarising filters should have little to no colour cast, but cheaper filters may tint the image. A way around this is to shoot the same subject without a polariser—that way, you have a reference image to work against when colour correcting.
- For live view cameras: if you’re rotating the polariser in Aperture or Shutter priority mode on your camera, you may not notice the effect because the camera’s exposure metering will be adjusted on the fly (it will compensate for the darkening). I tend to half-press the shutter button to lock the current exposure in place before rotating the filter so I can see the effect more clearly and get the correct rotation.
Polarisers and Affinity Photo
Since a polariser physically alters the light entering the lens, emulating its effects in post-production is tricky. Using Affinity Photo, we can however approximate some of a polariser’s benefits, including the reduction of haze and deeper saturation of certain colours:
Watch the above video to see how the Haze Removal filter works in Affinity Photo.