Neutral density filters are light-blocking glass that extend your exposure time without affecting colour. They are one of the most powerful tools in landscape and cityscape photography — transforming ordinary daylight scenes into something that feels painted rather than captured. Understanding which filter to use and when is the difference between a technically correct long exposure and a truly intentional one.

The Stop System

Each stop of ND doubles your exposure time. A 3-stop ND multiplies your base shutter speed by 8. A 6-stop ND multiplies by 64. A 10-stop ND multiplies by 1024. In practice: if your metered exposure without a filter is 1/125s, adding a 10-stop ND gives you approximately 8 seconds. Use the formula: Extended time = base time × 2^(number of stops).

3-Stop ND (ND8) — Moving Water in Low Light

At dawn or dusk when light levels are already dropping, a 3-stop ND extends waterfall exposures to 1–3 seconds for smooth, silky flow without going full abstract. This is my go-to filter for the waterfalls of North Georgia — Amicalola Falls and Anna Ruby Falls both respond beautifully to a 2-second exposure that blurs the water while retaining the rock texture and surrounding forest.

WSP Gear Note: I use the Sony 14mm GM with a step-up ring for ND work on ultra-wide shots. The Tamron 17-28mm f/2.8 takes 67mm filters which are more common and affordable. Always set focus before attaching any filter darker than 6 stops — live view can't lock focus through very dark glass.

6-Stop ND (ND64) — Daytime Long Exposures

The 6-stop is my most-used landscape filter. At midday with a base exposure of 1/500s at f/11 ISO 100, adding 6 stops gives you roughly 1/8s — still too fast for motion blur. But drop to f/16 and base drops to 1/250s, making your filtered exposure about 1/4s for a hint of water movement. Ideal for partially cloudy days where you want some cloud movement in the sky without going extreme.

10-Stop ND (ND1000) — The Transformer

This is where landscapes become paintings. A 10-stop ND at midday turns a 1/125s base into a 8-second exposure — enough to turn waves into mist, clouds into streaks, and crowds into ghosts. For Atlanta cityscape work, a 10-stop ND during rush hour turns the connector's traffic into pure light trails even in bright afternoon sun. The Sony A7RV with its 61MP sensor means you can afford to shoot at f/11 for maximum depth of field without significant diffraction softening.

Graduated ND Filters

A graduated ND (GND) darkens the sky while leaving the foreground unaffected — invaluable when shooting into a bright sky with a darker foreground. I use a 3-stop soft GND for most landscape scenes. The 'soft' edge blends across a wide transition zone, making it far more forgiving than a hard-edge GND when the horizon isn't perfectly flat. Align the transition zone with the actual horizon line by watching the live view as you slide the filter.

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