Filters in mountain photography: polarizing, ND, and GND

Polarizer, ND, and GND: three filters for three different problems

These three families are often grouped under the generic term "landscape filters," even though they don't address the same needs.

This distinction is fundamental. A polarizer acts on the nature of reflected light; an ND acts on the possible exposure time; a GND acts on the distribution of exposure within the frame.

What is a polarizing filter used for in mountain photography?

The circular polarizer is probably the filter whose effect is the most difficult to reproduce afterwards. Nikon reminds us that a polarizer can reduce reflections and enhance color saturation. In landscapes, this property is particularly visible on water, wet foliage, certain rocky surfaces, and the sky.

The principle of use is simple: mount the filter, then turn its ring while directly observing the effect in the viewfinder or on the screen. The intensity changes with rotation and with the angle between the light, the subject, and the camera.

The best position is not necessarily where the effect is maximum. This is even one of the most important rules in this guide: a polarizer should be dosed.

Nikon's technical presentation on polarizing filters notably confirms their usefulness in controlling reflections and enhancing colors in landscape scenes.

Should you use a polarizer to photograph a reflection on a lake?

Not necessarily. This is even a case where the expression "the polarizer removes reflections" can lead to a bad decision.

If the reflection of the summit in the lake is the main subject, removing it would obviously be counterproductive. However, slightly rotating the polarizer can sometimes reduce some of the surface glare, reveal stones underwater in the foreground, or balance an area of the lake without making the entire mirror disappear.

I therefore proceed by comparison:

1. observe the scene without a marked polarizing effect;
2. slowly turn the ring;
3. watch what changes in the reflection, but also in the sky and rocks;
4. stop as soon as the effect genuinely improves the composition.

The "technically most polarized" result is not necessarily the best photograph.

Our guide Photographing alpine reflections: mountain lakes and symmetrical compositions further discusses weather, wind, framing, and settings specific to reflections.

Why can a polarizer create an uneven sky with a wide-angle lens?

The effect of the polarizer depends on the angle relative to the light. It is generally particularly pronounced when the camera is aimed approximately at a right angle to the sun. With a wide focal length, the frame simultaneously covers a large portion of the sky: some areas can therefore be strongly polarized while others are much less so.

The result is a sky where one part becomes very dark blue while the other remains significantly brighter. In a panoramic image or an ultra wide-angle shot, this difference can attract more attention than the landscape itself.

How to avoid this effect?

• reduce the intensity of the polarizer instead of seeking its maximum;
• observe the entire sky, not just the area near the subject;
• remove the filter if the unevenness becomes more bothersome than the reflections it corrects;
• be particularly vigilant with very wide focal lengths and a uniformly blue sky.

The problem is much less visible when the sky is very cloudy or when the frame contains little sky.

Is a polarizer useful for photographing snow?

Yes, but it's not automatically beneficial. On snow, the polarizer can reduce some glare and enhance the contrast between a blue sky, rocks, and snowy areas. It can also improve the overall saturation of a winter scene under a clear sky.

But the snow must retain light. The small glints produced by crystals contribute to its fresh and luminous appearance. Too strong polarization can make certain surfaces duller and visually less lively.

The sky must also be taken into account: with a very wide view, the risk of uneven blue remains the same as in summer.

For exposure, white balance, whiteout, and blue shadows, consult our guide Photographing snow in the mountains: exposure, colors, and difficult conditions.

What is an ND filter used for in mountain photography?

An ND — Neutral Density — filter reduces the amount of light reaching the sensor as uniformly as possible. Its purpose is not to improve color or contrast: it mainly allows for the use of a slower shutter speed when there is too much light to achieve that exposure duration without a filter.

Canon, for example, explains that an ND filter allows control over shutter speed by reducing the light entering the camera. This is exactly the use we are interested in for water and clouds.

Situations where an ND is genuinely useful

• transforming a waterfall or stream into a smoother movement;
• lengthening an exposure on a lake when small ripples need to be smoothed out;
• making cloud movement visible over several seconds or tens of seconds;
• using a wide aperture in strong light when the camera's maximum shutter speed is not enough — more common in portraiture than landscape.

The Canon guide on water photography reminds us that an ND filter reduces light by a measured number of stops, thus providing more control over shutter speed.

When an ND is useless

If the light is already dim and you naturally get 1/2 second or several seconds at ISO 100 and your desired aperture, adding an ND filter brings no benefit. During blue hour, a strong ND can even force a much longer exposure than necessary and unnecessarily complicate the shooting process.

ND filter 3, 6, or 10 stops: which density to choose?

Density indicates how much light the filter blocks. Each additional stop doubles the exposure time needed at equal settings.

These values help understand the order of magnitude. The camera often calculates exposure correctly through modern filters, but knowing the logic allows you to choose the filter even before mounting it.

The 6-stop is often the most versatile in the mountains

For landscape use, a medium ND around 5 to 6 stops often offers a good compromise: strong enough to create movement during the day, but not to the point of turning every image into a multi-minute exposure. The 10-stop is more specialized.

I prefer a density adapted to the desired effect rather than the longest possible exposure. A waterfall completely transformed into a white sheet is not automatically more interesting than water at 1/4 or 1/2 second that still retains some structure.

What shutter speed to choose for a waterfall or stream?

The ND filter does not determine the rendering; it allows achieving the speed that determines it.

• 1/15 to 1/4 s: water begins to blur but retains a lot of texture;
• 1/2 to 2 s: significantly smoother rendering, very common in landscapes;
• several seconds: very smoothed water, more graphic rendering;
• tens of seconds: very pronounced effect, sometimes interesting on clouds or large bodies of water.

The actual speed depends greatly on the flow rate, distance, focal length, and intention. A fast stream can already appear very smooth at 1/4 s, while an almost still lake requires several seconds to visibly alter its surface.

Before mounting a powerful ND, I often take a test shot without a filter or with a low density. This avoids spending several minutes on an exposure that ultimately does not improve the composition.

What is a GND graduated filter used for?

A GND — Graduated Neutral Density — is not uniformly dark. One part is transparent, another is darkened, with a more or less progressive transition between the two. It is primarily used to reduce the luminosity difference between a bright sky and a darker foreground.

LEE Filters precisely describes GNDs as filters designed to balance exposure in a scene, typically between a bright sky and darker terrain. Systems exist with different strengths and transitions — soft, medium, hard, or even very hard depending on the ranges.

Manufacturer reference: LEE Filters — graduated ND filters.

Soft, medium, or hard?

The hard transition is suitable for a very clear horizon, like the sea. In the mountains, the horizon is rarely a straight line: summits, passes, and valleys cross the transition. A soft or medium gradation is therefore generally easier to use because it darkens less abruptly the features that extend into the sky.

Why are mountains difficult to photograph with a GND?

This is the main limitation of the graduated filter in alpine landscapes. The filter has a relatively simple geometric transition; a mountain range has a complex line.

If you lower the GND to properly darken the sky, the summits rising into that area are also darkened. A high peak can become artificially dark while the valley below the filter line remains normal.

In this type of landscape, a soft GND can still be useful if the light difference is significant, but I remain cautious about its strength. A 2-stop filter with a soft or medium transition is often more natural than a very strong gradient that immediately makes the darkened area visible.

Should you still use a GND with modern sensors?

The GND is probably the filter whose usefulness has evolved the most with digital photography. A modern RAW file often retains enough dynamic range to recover a slightly overexposed sky or open up a dark foreground without a filter. When the difference becomes truly significant, a series of bracketed exposures can then be merged.

Nevertheless, the GND still offers several advantages:

• see a balance closer to the final result immediately in the viewfinder;
• reduce the brightness difference before recording and make more use of the sensor's dynamic range;
• avoid exposure blending when elements move between frames;
• limit post-processing time if the filter matches the scene well.

Conversely, bracketing is often more precise around a complex mountain range, as it does not impose a physical dark band on the peaks.

Is a reverse GND useful for sunrise or sunset?

A reverse GND has its strongest density near the transition line, then lightens towards the top. It is designed for situations where the brightest area is near the horizon, typically a low sun.

On a seascape, this is very logical. In the mountains, the benefit largely depends on the relief's silhouette. A sunset behind a mountain pass can match the filter's structure quite well. A succession of high and low peaks makes the effect much more delicate.

So I wouldn't rank it among the first filters to buy for mountain photography. A good polarizer and a versatile ND will generally have more opportunities to be used.

To anticipate the sky/relief balance at the right time, consult our guides on golden hour, sunset, and sunrise in the mountains.

Can you stack a polarizer, an ND, and a GND?

Yes, technically, but each additional layer can create constraints:

• risk of vignetting with a very wide focal length;
• more surfaces likely to create internal reflections or flare;
• additional light loss with the polarizer;
• longer manipulations in wind, cold, or rain;
• risk of leaving drops or marks between filters.

On a tripod and in a calm situation, a polarizer combined with an ND can be very effective for a waterfall or stream. However, I don't mount three filters just because I have them in my bag. Each filter must bring something visible.

Beware of vignetting with wide-angle lenses

A thick filter holder, multiple screw-in rings, or a polarizer mounted in front of another filter can appear in the corners with some very wide focal lengths. Check the frame at the minimum focal length before starting a long exposure.

Screw-in filters or filter holder system?

Screw-in filters

They are compact, quick to transport, and very practical for a polarizer or an ND. Their main constraint is the lens diameter. Adapter rings allow a large filter to be used on several lenses of smaller diameters.

Square or rectangular filter holders

They become particularly interesting for GNDs, as you can vertically move the transition instead of leaving it fixed in the center of the frame. It is also practical for combining several densities.

In the mountains, the compromise is also logistical: a rectangular system takes up more space and requires more manipulations. If you rarely use GNDs, carrying only a CPL and screw-in ND might be more consistent.

How to avoid color casts with an ND filter?

An ideal ND filter should only reduce the amount of light, without changing the color. In practice, some filters—especially strong densities or certain variable models—can introduce a warm, cool, green, or magenta cast.

RAW allows for correcting some of these drifts, but a heavily colored filter complicates the work, especially if several images need to be assembled.

Before an important outing:

• photograph the same scene with and without the filter;
• compare white balance and colors;
• check the corners of the image;
• test the maximum densities of a variable ND, where irregularities can be more visible depending on the model and angle.

A filter is an optical element added in front of an often expensive lens: its actual quality matters.

How to use filters with snow and ski touring?

In winter, I would be even more minimalist. Handling multiple plates or rings with gloves takes time and exposes the lens more to snow. The polarizer is the easiest filter to justify when a blue sky or glare needs to be controlled, but you have to monitor the rendering of white and variations in the sky.

An ND is much less useful for an action scene, since the goal is usually to get a high shutter speed. It regains its usefulness if the outing includes a waterfall, a stream, or a static scene where a long exposure really adds something.

The guide Photography in mountaineering: equipment, cold, condensation, and safety separately addresses carrying, batteries, gloves, and condensation.

Which filter to bring depending on the outing?

If I had to bring only one filter

For a mountain photography outing without a highly specialized subject, I would choose the polarizer. Its effect on certain reflections cannot be properly recreated in post-processing, and it remains compact. For an outing focused on waterfalls or long exposures, the ND obviously becomes a priority.

If I had to put together a simple kit

• a good circular polarizer;
• a medium ND around 5 to 6 stops;
• possibly a soft or medium 2-stop GND if you actually use it in the field.

I prefer this reduced kit to a collection of densities that you never learn to master.

The most common mistakes with filters in the mountains

Leaving the polarizer permanently attached

It reduces light and alters the scene even when this effect is not useful. Remove it when you can't explain what it's contributing.

Systematically maximizing polarization

A partially preserved reflection or a less dark sky can produce a much more natural image.

Choosing the strongest ND

A two-minute exposure is not intrinsically better than a one-second exposure. Choose a shutter speed, then the density that allows you to achieve it.

Aligning a GND on a mountain as you would on a sea horizon

The transition will also darken the peaks. Observe the relief line precisely.

Stacking filters without checking the corners

Mechanical vignetting may only become visible at the shortest focal length.

Forgetting about drops, dust, or smudges

A long exposure in backlight can sometimes make flaws very visible that are difficult to spot on the back screen.

A filter must solve a visible problem in the image

The polarizer, ND, and GND are three very different tools. The first controls certain reflections, the second allows for slower shutter speeds, and the third reduces a brightness difference within the frame. None are mandatory for creating good mountain photography.

The polarizer is the one whose effect is least replaceable in post-processing. The ND becomes essential when motion needs to be recorded for a duration impossible without reducing light. The GND remains useful, but today it must be weighed against the dynamic range of RAW files and bracketing, especially when the mountain ridge line makes its transition visible.

The best reflex is therefore to look at the scene before looking at the filter pouch: what photographic problem do I need to solve? If the answer is clear, the choice of filter usually is too.