Reciprocity!

Reciprocity easily calculates exposure settings for great pictures every time. Great for anyone, from beginners to seasoned photographers. Features:* Instantly calculate Exposure value, ISO speed, Aperture, or Shutter Speed* Enter values either directly or via a slider* Option to choose Exposure value from a list of common scenes* Convert exposure settings between different cameras or film speeds* Save the reciprocity failure values of multiple films for future use* Round exposure stop values to 1/2, 1/3 or both* Built-in timer for exposure longer than 2 seconds* Detailed user guide to help beginners make use of their cameras manual settings