Lee ND Exposure Calculator
Enter your metered shutter speed, select your Lee filters, and get the corrected long-exposure time instantly.
What this Lee filters calculator does
Neutral density filters reduce the amount of light entering your lens. Every full stop halves the light, which means you must double exposure time to keep brightness constant. This calculator automates that math so you can move quickly in the field, especially when working with long exposures for waterfalls, seascapes, clouds, and city scenes.
It is designed around popular Lee filters such as the Little Stopper, Big Stopper, and Super Stopper, while still allowing custom stop values for stacked setups or non-standard combinations.
How stop-based exposure math works
The core formula
If your base shutter speed is known, adjusted shutter speed is:
Adjusted Time = Base Time × 2Total Stops
Example: if your base is 1/125 second and you add a 10-stop Big Stopper, your new shutter time is: 1/125 × 210 = 8.192 seconds.
Why this matters in real shooting
- Fast estimate in changing light conditions.
- Fewer missed moments during sunrise/sunset transitions.
- More reliable long exposures once times move beyond 30 seconds.
- Cleaner workflow when stacking multiple ND filters.
Common Lee filter combinations
These pairings are frequently used by landscape photographers:
- Little Stopper (6 stops): soft water movement with manageable shutter times.
- Big Stopper (10 stops): dramatic cloud streaks and crowd removal in urban scenes.
- Super Stopper (15 stops): ultra-long daytime exposures for very smooth skies and water.
- Big + Little (16 stops total): extreme long exposure work where bulb mode is required.
How to use this calculator in the field
Step-by-step workflow
- Compose and focus without heavy ND filters mounted.
- Meter your base exposure and enter the shutter speed here.
- Select your Lee filter(s) or enter a manual total stop value.
- Apply the result on camera; switch to bulb mode when needed.
- Re-check histogram and refine for changing light.
Practical tips for better results
- Cover the viewfinder during long exposures to avoid stray light leaks.
- Use a remote trigger or intervalometer for exposures over 30 seconds.
- Enable long exposure noise reduction if your workflow allows the extra time.
- Bracket around the calculated value when light is rapidly shifting.
FAQ
Does this calculator work for any ND brand?
Yes. The stop math is universal. The Lee presets are included for convenience, but you can enter any custom stop amount.
Should I include ND grads in the total?
Usually no for global exposure time, because grads affect only part of the frame. Include them only if they effectively reduce the overall metered scene in your specific setup.
Why does my final image still need adjustment?
Very long exposures can be influenced by changing light, sensor behavior, and filter tolerances. Treat the calculated value as an accurate starting point, then fine-tune with histogram feedback.