Behind the frame / Exposure

Shutter after Stop Change: from inputs to a useful answer

Each additional stop doubles exposure time at a fixed aperture and scene.

Initial time compared with the result of Shutter after Stop Change; the example conditions stay fixed
Figure 1. Calculated scenarios for shutter after stop change. The highlighted point uses the example input. Lines connect sampled points and do not imply valid fractional counts.

Start with the relationship

The question this tool answers is specific: given initial time, more exposure, what value follows from the stated model? The result is expressed in s. The calculation below makes that relationship visible, so the answer can be checked independently instead of accepted as an unexplained number.

initial time × 2^stops

Keep capture settings, physical dimensions and delivery requirements in separate columns of the job notes. A mathematically equivalent setting may change motion blur, depth of field or noise. Check an actual frame before committing an entire session to a numerical estimate.

A worked example

Use the following values as a reproducible starting point. They are illustrative inputs, not measurements of your situation or a recommendation for a particular project. The calculator opens with the same values, making it possible to compare a manual calculation with the on-screen answer.

InputExample valueUnit
Initial time0.008s
More exposure2stops

Substitute these quantities into the displayed relationship: initial time = 0.008 s; more exposure = 2 stops. Carry out the operations before rounding the final value. This gives 0.032 s. The number is a result for this particular set of inputs; changing the measurement basis or the conditions can change its practical meaning.

What changes when an input changes?

In the illustrated range, changing initial time from 0.0048 to 0.0112 s moves the result from 0.0192 to 0.0448 s. The output increases between those endpoints. The table gives intermediate samples so you can see whether the response is smooth, stepped or nonmonotonic; the endpoints alone do not establish that behaviour.

Every other input keeps the value shown in the example table. This controlled comparison isolates one relationship at a time. For a real decision, try a lower, central and higher plausible input instead of treating an uncertain measurement as perfectly exact.

Initial time (s)Result (s)
0.00480.0192
0.00640.0256
0.0080.032
0.00960.0384
0.01120.0448

The assumption that matters

Positive values lengthen the exposure. Motion blur and clipping may constrain the usable setting.

A valid numerical result only means the entered values can be evaluated by this formula. It does not confirm that the formula describes every feature of the real situation. Read the unit labels, check the measurement method and keep the specific limitation above with the result when sharing it.

Use the result in your own work

Open the calculator, replace the example values and select Calculate. The result is evaluated on your device. Reset example restores this article's scenario, while Copy result keeps the quantity and unit together. If an input is outside the model's allowed range, correct it before interpreting the output.

Keep more digits during a chain of calculations than you show in a finished note. Displayed values are rounded for readability; extra decimals do not make a rough measurement more accurate. When your decision depends on a tight tolerance, compare the original measurements and assumptions before relying on the last displayed digit.

Open Shutter after Stop Change

Further reading & method notes

Adobe — image resolution for print provides background for this subject. This article's numerical examples and chart were calculated from the formula shown above. See the editorial policy for how this collection presents assumptions and corrections.

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