ND Filter Calculator
This ND filter calculator computes the new shutter speed after adding a neutral density filter. A 1/250s base shutter with ND1000 (10 stops) becomes 4.096 seconds. Enter any shutter speed and select your filter to get the adjusted exposure instantly — supports ND2 through ND4000.
Result
Frequently Asked Questions
How do I calculate shutter speed with an ND filter?
Multiply the base shutter speed by 2^(number of stops). Formula: New Shutter = Base Shutter × 2^stops. Example: 1/250s with a 10-stop ND1000 filter: 1/250 × 2^10 = 1/250 × 1024 = 4.096 seconds.
What is ND1000 in stops?
ND1000 is a 10-stop neutral density filter. It reduces light by a factor of 1000 (roughly 2^10 = 1024). An ND1000 filter turns a 1/250s shutter into a 4-second exposure, allowing for long exposures in daylight.
What is the difference between ND8 and ND64?
ND8 is a 3-stop filter that reduces light by 1/8th. ND64 is a 6-stop filter that reduces light by 1/64th. ND8 is useful for light motion blur; ND64 gives longer exposures for more dramatic effects. An ND64 at 1/250s gives a 1/4-second exposure.
When should I use an ND filter?
Use ND filters when: shooting silky water or waterfalls in daylight (ND8–ND64), maintaining cinematic shutter speeds for video in bright light (ND4–ND64), shooting wide-open aperture portraits outdoors (ND2–ND8), or creating cloud-movement blur in long exposures (ND1000+).
What does ND stand for?
ND stands for Neutral Density. Neutral means the filter doesn't affect color balance — it absorbs light equally across all wavelengths. Density refers to how opaque the filter is. A higher ND number means more light is blocked.
Is ND1000 the same as a 10-stop filter?
Yes. ND1000 (or ND10.0 in some notations) = 10 stops. The number after 'ND' is approximately the light-reduction factor: ND1000 blocks 1000× more light. Since each stop halves the light, 2^10 = 1024 ≈ 1000. Some manufacturers label the same filter as 'ND 3.0' (optical density notation) or '10 stops'.
Can I stack ND filters?
Yes, stacking ND filters adds their stops together. Stacking ND8 (3 stops) and ND64 (6 stops) gives 9 stops total. However, stacking can cause vignetting (dark corners), loss of sharpness, and color casts. A single high-stop filter like ND1000 usually produces better image quality than stacking.
What is the 180° shutter rule in video?
In cinematography, the shutter speed should be approximately double the frame rate: 1/50s for 25fps, 1/48s for 24fps, 1/60s for 30fps. This creates natural-looking motion blur. In bright sunlight, an ND filter is needed to maintain this shutter speed without overexposing.
ND Filter Formula
An ND (neutral density) filter reduces the amount of light entering the lens without affecting color. Each stop halves the light, so the shutter speed must double to maintain exposure.
New Shutter = Base Shutter × 2^stops
Example: 1/250s × 2^10 = 1/250 × 1024 = 4.096 seconds with ND1000 (10 stops)
ND Filter Reference Table
| Filter | Stops | Light reduction | 1/250s becomes |
|---|---|---|---|
| ND2 | 1 | 50% | 1/125 |
| ND4 | 2 | 25% | 1/60 |
| ND8 | 3 | 12.5% | 1/30 |
| ND16 | 4 | 6.25% | 1/15 |
| ND64 | 6 | 1.56% | 1/4 |
| ND1000 | 10 | 0.1% | 4.1s |
| ND4000 | 12 | 0.024% | 16.4s |
When to Use ND Filters
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