Exposure Calculator (ND Filter)
Calculate precise exposure adjustments when using ND (Neutral Density) filters. Get instant shutter speed, ISO, and aperture compensations for any ND filter strength—from ND8 to ND1000 and beyond.
ND Filter Conversion Table
Quick reference for converting between ND filter rating systems:
| ND Number | Optical Density | Stops | Light Transmission |
|---|---|---|---|
| ND2 | 0.3 | 1 stop | 50% |
| ND4 | 0.6 | 2 stops | 25% |
| ND8 | 0.9 | 3 stops | 12.5% |
| ND16 | 1.2 | 4 stops | 6.25% |
| ND32 | 1.5 | 5 stops | 3.125% |
| ND64 | 1.8 | 6 stops | 1.56% |
| ND256 | 2.4 | 8 stops | 0.39% |
| ND1000 | 3.0 | 10 stops | 0.1% |
Example Exposure Times with ND Filters
See how ND filters transform your shutter speeds for long exposure photography:
| Original Shutter | + ND8 (3 stops) | + ND64 (6 stops) | + ND1000 (10 stops) |
|---|---|---|---|
| 1/1000s | 1/125s | 1/16s | 1s |
| 1/500s | 1/60s | 1/8s | 2s |
| 1/250s | 1/30s | 1/4s | 4s |
| 1/125s | 1/15s | 1/2s | 8s |
| 1/60s | 1/8s | 1s | 16s |
Usage: ND8 for subtle motion blur, ND64 for silky water/clouds, ND1000 for extreme long exposures in daylight. When using ND filters to achieve longer exposures, understanding your depth of field becomes crucial, as wider apertures (often used with ND filters) create shallower focus zones.
Related Photography Calculators
Complete your photography toolkit with these calculators:
- Golden Hour Calculator: Find the best times for natural light photography with warm, diffused golden hour lighting.
- Timelapse Calculator: Plan timelapse sequences with ND filters for smooth daytime timelapses of clouds, traffic, and more.
- Depth of Field Calculator: Calculate focus range when using ND filters to shoot wide open in bright light for shallow depth of field.
Frequently Asked Questions
Q:What is an ND filter?
An ND (Neutral Density) filter is a piece of darkened glass that reduces the amount of light entering your camera lens without affecting color. Think of it like sunglasses for your camera. ND filters allow you to use slower shutter speeds or wider apertures in bright conditions, enabling creative effects like motion blur in waterfalls, silky clouds, or shallow depth of field in sunlight.
Q:How many stops of ND filter do I need?
It depends on your shooting conditions and desired effect. For landscape photography with motion blur in daytime: use 3-6 stops (ND8-ND64) for slight blur, 6-10 stops (ND64-ND1000) for smooth water and silky clouds, or 10+ stops (ND1000+) for extreme long exposures turning moving water to glass. For portraits in bright sun to use wide apertures: 2-3 stops (ND4-ND8) is usually sufficient.
Q:What is the difference between ND8, ND64, and ND1000?
These numbers indicate the filter factor—how many times longer your exposure needs to be. ND8 = 3 stops (8× longer exposure), ND64 = 6 stops (64× longer), ND1000 = 10 stops (1000× longer). For example, if your correct exposure is 1/1000s without a filter, with ND1000 you'd need 1 second. ND8 is suitable for slight motion blur, ND64 for daytime long exposures, and ND1000 for extreme long exposures in bright sunlight.
Q:How do I convert ND density to stops?
Divide the density value by 0.3 to get stops. For example: ND 0.9 = 0.9 / 0.3 = 3 stops. ND 3.0 = 3.0 / 0.3 = 10 stops. Conversely, multiply stops by 0.3 to get density: 6 stops × 0.3 = ND 1.8 density. Different manufacturers use different notation systems, so this conversion is helpful when comparing filters.
Q:Can I stack multiple ND filters?
Yes, you can stack ND filters to add their stop values together. For example, stacking a 3-stop (ND8) and a 6-stop (ND64) gives you 9 stops total. However, stacking too many filters can cause vignetting (darkening at corners), reduce sharpness, and increase reflections. Variable ND filters (which rotate to adjust strength) are often better than stacking for flexibility.
Q:Do I need to change ISO or aperture with an ND filter?
Not necessarily. The most common approach is to adjust only shutter speed—this is why we use ND filters, to get longer exposures. However, you CAN compensate by lowering ISO or closing down aperture instead if your creative goal doesn't require a slower shutter. For example, if you want motion blur, adjust shutter speed. If you just want to reduce light for wider aperture depth of field, you might keep shutter the same and adjust ISO.