With Shutter-Speed you can test the Shutter speeds of your analog cameras just with your iPhone.
Please note that the full potential of this App is only reached if you use it in combination with the PhotoPlug. The PhotoPlug is an optical sensor which connects to the headphone-jack of your iPhone and enables you to measure the actual amount of light passing through the camera shutter.
Please visit www.photoplug.de for detailed information and instruction.
The App also allows you to save the measured values into a handy table. Furthermore, the App automatically calculates a correction factor, which allows you to compensate a faulty shutter speed. For example, if you measure the 1/60s and it turns out to be just 1/50s, the App will tell you that the shutter-speed is 1/3 f-stops too long. This gives rise to a correction factor of -1, indicating that you have to close your aperture by 1/3 f-stop to get a correct exposure.
Updated AppStore description
Ratings and Reviews
Works very well
This app is excellent - zooming in/out on the waveform works nicely and it is easy to position and save measurements to the many mechanical cameras I own. It seems quite accurate between 1/1 and 1/15 even just using the built-in microphone, and that's plenty for me to perform simple checks for slow shutter speed accuracy. I've been using it mainly with SLR's, with the film door open and holding the mic close to the shutter mechanism.
For old large format lenses to measure their accuracy to be able to compensate if necessary.
Useful for testing analog cameras
A good idea for folks who work with older, analog cameras - the simple idea here is that you can listen to the shutter or, with a simple light sensor available from the author, examine the light coming through the shutter and determine the shutter speed. The app provides a database for you to store results by camera.
There are room for improvements (the application doesn't try and do its own analysis of the data, it's up to you; the application makes assumptions about possible shutter speeds) but those of us who need this kind of application will probably find it useful nonetheless.
With Family Sharing set up, up to six family members can use this app.