6XC

ND Filter Exposure Calculator

Convert your base shutter speed through any ND filter (ND8, ND64, ND1000, stacked) — with a built-in countdown timer for long exposures.

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New Exposure Time—
Total Stops—
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How ND Filter Math Works

Each stop of neutral density doubles the exposure time: new shutter = base shutter × 2^stops. An ND8 is 3 stops, ND64 is 6, ND1000 is 10 — so a 1/60 s meter reading becomes 17 seconds behind an ND1000. Stack two filters and their stops add. Meter and compose without the filter, calculate here, screw the filter on, switch to bulb mode and use the built-in countdown timer — it beeps when your exposure is done.

Frequently Asked Questions

What shutter speed with a 10-stop ND at 1/125?

1/125 × 1024 ≈ 8 seconds. Common results with ND1000: 1/60 → 17 s, 1/30 → 34 s, 1/15 → about 1 minute.

Can I stack ND filters?

Yes — stops add: ND8 (3) + ND64 (6) = 9 stops. Watch for vignetting on wide lenses and slight color casts that multiply with cheap filters.

Why is my long exposure brighter than calculated?

In dim light, reciprocity is fine on digital, but light often changes during exposures over 30 s (clouds, dusk). Bracket by ±1 stop, and add roughly a stop of extra time as dusk deepens.

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