Polarisers and ND filters for New Zealand landscapes

Software can do a lot these days, but two kinds of filter still earn their place in a landscape bag: the polariser and the neutral density (ND) filter. Neither can be faked convincingly in editing, and both suit the kind of scenery New Zealand throws at you. Bush, water, wet rock and big skies.

The polariser

A circular polariser cuts down reflected, polarised light. In practice that does three useful things:

• Removes glare from water, so you see through the surface to rocks and weed below.
• Cuts the shine on wet leaves and rock, which lets the real colour come through. In damp native bush this can transform a shot.
• Darkens blue sky and makes clouds stand out.

You rotate the front ring while looking through the viewfinder or at the screen, and stop when the effect looks right. More isn’t always better.

Where the sun needs to be

A polariser’s effect on the sky is strongest when you’re pointing at about 90 degrees to the sun, and weakest when the sun is directly behind you or in front of you. A quick field trick: point your index finger at the sun and stick your thumb up. Rotate your hand, and wherever your thumb points is the band of strongest polarisation.

When it goes wrong

• Wide-angle lenses: a very wide lens takes in a big slice of sky at different angles to the sun, so the polariser darkens part of it more than the rest. You get an odd dark band across a blue sky. Back the effect off or skip the polariser for wide skies.
• Rainbows: a rainbow is polarised light, so a polariser can make it vanish. Rotate carefully, or take it off.
• Light loss: a polariser typically costs you somewhere between one and two-and-a-half stops of light. In dim bush that can push your shutter speed too slow for handheld shooting.

Neutral density filters

An ND filter is just dark glass. It cuts light evenly across the frame so you can use a longer shutter speed or wider aperture than the conditions would normally allow.

Reading the numbers

ND filters are labelled in a few different ways, which is confusing until you see the pattern. Each stop halves the light:

So an “ND8”, an “ND 0.9” and a “3-stop ND” are all the same strength.

Which strength for what?

• 3 stops: takes the edge off on bright days. Good for slightly softening a small stream, or shooting a wide aperture portrait in sun.
• 6 stops: the most useful all-rounder for waterfalls and surf. A 1/60 second exposure becomes about one second.
• 10 stops: the “big stopper” look. Clouds streak, the sea turns to mist, and a 1/30 second exposure becomes around 30 seconds.

Long exposure basics

• A solid tripod. Coastal wind will find any wobble.
• A remote release or the camera’s self-timer.
• Compose and focus before fitting a strong ND, because you won’t see much through it afterward. Then switch to manual focus so the camera doesn’t hunt.
• On a DSLR, cover the eyepiece. With a strong ND, stray light coming in through the viewfinder can affect the meter and sometimes leave a haze on the image.
• Expect a colour cast with cheaper strong NDs. Shooting RAW makes it easy to fix.

Graduated ND filters

A grad is dark at the top and clear at the bottom. It holds back a bright sky so the land and sky are both well exposed in one frame.

• Hard grads suit flat horizons, like the sea.
• Soft grads suit broken horizons, like hills and trees.

Plenty of photographers now skip grads and blend two exposures in editing instead. It’s free and handles awkward horizons better. Grads still save time, though, and some people simply prefer getting it right in camera.

Screw-in or square system?

Screw-in filters are compact and quick, and a decent polariser is the best first buy. Get one for your largest lens and use step-up rings for the smaller ones.

Square filter systems use a holder on the front of the lens. They make stacking a polariser, ND and grad easy, but they’re bulkier and fiddlier in wind.

Staying safe while you’re at it

Long exposures tend to happen in tricky places: rock platforms, river edges, coastal headlands at dusk. Your attention is on the screen, not the sea.

• Check the MetService marine forecast for swell and wind before a coastal shoot.
• Never set up on a rock shelf where waves are washing through, however good the composition looks.
• For bush waterfalls, rivers rise fast after rain. DOC’s know before you go advice is worth reading before heading into the hills.
• Keep your tripod legs out of fragile plants and stay on the track.

Our suggested starter kit

1. A good-quality circular polariser for your main landscape lens.
2. A 6-stop ND, which covers most waterfall and coast situations.
3. Add a 10-stop later if you fall for long exposures.

If exposure settings still feel like guesswork, start with our exposure triangle guide before buying any filters.