Shutter-Speed is a handy utility app for iPhone that allows you to test the shutter speeds of your analog cameras. With just your iPhone, you can accurately measure the speed at which the camera shutter operates.

To fully utilize the app's potential, it is recommended to use it in combination with the PhotoPlug. The PhotoPlug is an optical sensor that connects to the headphone jack of your iPhone. It enables you to measure the actual amount of light passing through the camera shutter, providing precise results.

In addition to measuring shutter speeds, Shutter-Speed also provides a convenient table for saving the measured values. The app automatically calculates a correction factor, allowing you to compensate for any inaccuracies in the shutter speed. For example, if you measure a speed of 1/60s and it turns out to be actually 1/50s, the app will inform you that the shutter speed is 1/3 f-stops too long. It suggests a correction factor of -1, indicating that you need to close your aperture by 1/3 f-stop to achieve the correct exposure.