Enter the equivalent focal length (mm) into the Calculator. The calculator will evaluate the Shutter Time.

## Shutter Time Formula

ST = 500 / EFL

Variables:

- ST is the Shutter Time (seconds)
- EFL is the equivalent focal length (mm)

To calculate Shutter Time, divide a value of 500 by the equivalent focal length in millimeters.

## How to Calculate Shutter Time?

The following steps outline how to calculate the Shutter Time.

- First, determine the equivalent focal length (mm).
- Next, gather the formula from above = ST = 500 / EFL.
- Finally, calculate the Shutter Time.
- After inserting the variables and calculating the result, check your answer with the calculator above.

**Example Problem : **

Use the following variables as an example problem to test your knowledge.

equivalent focal length (mm) = 20