Quick answer

Choose a 1-stop ND for subtle exposure control in bright conditions, a 6-stop for strong motion blur and wider apertures outdoors, and a 7-stop for extreme brightness like direct sunlight or long exposures.

How ND stops affect your image

Each ND stop halves the light reaching your sensor. A 1-stop filter (ND 0.3) is subtle—it lets you open your aperture by one stop without overexposing. A 6-stop (ND 1.8) and 7-stop (ND 2.1) are much stronger, letting you use wide apertures or slow shutter speeds even in midday sun. The trade-off: stronger filters can introduce color casts, but NiSi's Full Spectrum design minimizes this shift across the visible spectrum.

Frequently asked questions

When should I use a 1-stop ND filter?

Use a 1-stop ND when you need just a little more exposure control—for example, to avoid clipping highlights while keeping your current aperture and shutter speed. It's also useful for matching exposure across lenses with slightly different T-stops.

What's the difference between 6-stop and 7-stop ND filters?

A 6-stop filter (ND 1.8) reduces light by 64x, while a 7-stop (ND 2.1) reduces it by 128x. The extra stop matters in very bright conditions: if you're shooting at f/2.8 in direct sunlight and want a 1/50s shutter for a cinematic look, the 7-stop gives you that extra margin. The 6-stop is usually enough for overcast or shaded scenes. If you often shoot in full sun, consider the 7-stop as your primary filter and the 6-stop as a backup.

Can I stack rear ND filters?

Stacking rear ND filters is not recommended because it can introduce vignetting, reduce image sharpness, and cause color shifts. Instead, choose a single filter with the right stop strength for your scene.

Do these filters work with all ATHENA PL mount lenses?

Yes, the NiSi ATHENA rear PL filters are specifically designed for ATHENA PL mount lenses. They fit securely behind the lens and do not affect the front diameter or lens hood.

Filter options