Many landscape or outdoor photographers would be lost without a circular polarising lens (CPL) filter. By rotating a circular polarising filter, your camera lens can block out certain wavelengths of light. This lets you reduce glare, haze and reflections from objects such as water, glass or vehicles. It’s also great for darkening a sky to add a bit of drama to your shots.
Although circular polarising filters have many great uses, there are some occasions when they do more harm than good. In such cases, they should be left off your lens.
Wet look photography
If you want to highlight water on an image, this isn’t always easy to achieve through photography, as water is transparent. For example, you can’t always tell the difference between a wet or a dry rock in a photo. By removing your CPL filter, you can, however, let your lens capture light shining off droplets of water, thus creating a wet, shimmery look on surfaces.
We tend to think of reflected light as negative in photography, attempting to eliminate it as much as possible with a circular polarising filter. But, there are some instances where reflected light can actually add drama and visual appeal to a photo, such as a brightly coloured sunset, in which case it would be best not to use a CPL filter. In particular, if the reflected colour takes on a different or unusual hue, this can make an image interesting and unique.
Reflections on water are the bane of a landscape photographer’s life, but, occasionally, you might think they look pretty cool. If you want to keep the reflections but lose the nuisance glare while ensuring colour saturation is boosted, you can still enjoy the best of both worlds. You’ll need to take two shots, one with a polariser and the other without. With the help of some post-production trickery, you can blend the two exposures, taking the best bits from each photo.
Reflections to add depth
Sometimes you might want to introduce reflections, such as a shadow, to give a sense of depth to an object. For example, if you take a picture of a coloured ball, it might just look like a flat disk. Adding a slight reflection off the curved surface gives it a realistic, three-dimensional effect. In this case, don’t use a circular polarising filter.
When you take photos at night, a CPL filter will only serve to reduce light to your lens, which is the last thing you’ll want when it’s already pitch black. Leave your CPL filter off your lens in this scenario. Similarly, it’s not worth using a circular polarising filter in very low light or completely shady areas, as glare or reflections won’t be an issue.
Another scenario dictating when not to use a circular polarising filter is if you shoot rainbows. A rainbow is actually just reflected light, so if you stick a polariser on your lens, the rainbow will vanish. Simply take your CPL filter off, and it will reappear.
Circular polarising filter on a wide-angle lens
It’s generally not a good idea to use a circular polarising filter with a wide-angle lens. This is because CPL filters work best when they’re at a 90-degree angle away from a light source, such as the sun, and a wide-angle lens usually covers more than 90 degrees. This results in an uneven polarising effect in your photo.