ND4096: twelve stops
Twelve stops, a factor of 4096: 1/125 s becomes almost 33 seconds. This strength solves one particular problem: long exposure when the sun is high and ten stops are not enough.
- Stops12
- Filter factor4096×
- 1/125 s becomes32.768 s
What this strength is good for
- Long exposure in full sun: At midday by the sea at f/11 and ISO 100, ten stops land you at two or three seconds, which is too short for glassy water. Twelve stops bring the same scene to half a minute.
- Architecture without passers-by: The longer the exposure, the less of any movement survives. At a minute a busy forecourt is empty, without anyone waiting or retouching.
- When stacking is not an option: Twelve stops could also be built from ND64 plus ND64. Two filters mean four extra glass surfaces, more stray light, and on a wide angle lens dark corners arrive quickly.
Calculating with ND4096
Pick a shutter speed. The fields are preset to ND4096.
HMINSECMS
00:00:32:768
hours : minutes : seconds : milliseconds
Exposure times with ND4096
On the left the speed your camera suggests without a filter, on the right what it becomes.
| No filter | With ND4096 |
|---|---|
| 1/500 | 8.2 s |
| 1/250 | 16.4 s |
| 1/125 | 32.8 s |
| 1/60 | 1 min 8 s |
| 1/30 | 2 min 17 s |
| 1/15 | 4 min 33 s |
| 1/8 | 8 min 32 s |
| 1/4 | 17 min 4 s |
| 1/2 | 34 min 8 s |
| 1 s | 68 min 16 s |
What to watch for
- Almost always bulb: At this strength you rarely stay under 30 seconds. A remote release with a lock, or a timer, stops being an accessory and becomes a requirement.
- Light leaking at the holder: With square filter systems, exposures this long let light in at the side between filter and holder and brighten one edge. A gasket, or a cloth thrown over the holder, deals with it.
- The colour cast becomes the job: What is correctable at ten stops turns into the main task in editing at twelve. This is where better glass genuinely pays off, unlike at the weak strengths.
- The scene has to move: Half a minute on a still subject is half a minute without an effect. This strength only pays where water, clouds or people are in motion.
The ND4096 is a specialist. People who need it usually know it already. Anyone unsure will get further with an ND64 and an ND1000.
The other strengths
Not sure which strength yet? Which ND filter? works from the subject to the number of stops.
Every value from ND2 to ND8192 is in the ND filter table, and the FAQ answers the common questions.