System Requirements

• The f-Stop Printing Calculator app has a minimum system requirement of Apple iOS 6.0+ or Android 3.0+. It works on all iPhones, iPod Touches, iPads and Android devices.

How safe is the red light mode?

• You can turn on/off the red light mode by clicking the lightbulb icon in the bottom right corner. Please be aware that many devices, including all iOS devices, use a white backlight that cannot be turned off. This means that it is impossible to use the red light mode as a genuine safelight. The red light mode is designed to reduce the white light as much as possible, but you should still turn the brightness down to its minimum level on your device and be sure to keep the device as far as possible (minimum 1 meter) from any light-sensitive material such as film and paper. We strongly recommend that you perform your own tests to determine light safety. The red light mode is provided for occasional convenience: the best practice is to determine your exposure in normal mode, then set your timer and load the paper with the screen off. You may want to employ Airplane mode when in the darkroom to avoid incoming text or calls from lighting up the screen.
  
  NB: the number picker and other menu items on the Android version and pre-iOS7 versions of the app are not masked in red, so the device should never be in close proximity to any light-sensitive materials.

Who created this app?

• The functions and algorithm used in the f-Stop Printing Calculator were designed by Bruce Tanner. The app was built by Digitaltruth Photo Ltd.

I need more help

• Please visit the Support Forum