A new tool is available on the Apple Store to calculate optimum camera settings to get maximum sharpness. OptimumCS runs on iPhone and iPod Touch devices and is designed for photography where maximum sharpness over a large depth of field is required such as landscape, architectural, and travel photography.
OptimumCS simply tells the photographer what aperture to use and at what distance to focus after determining focal length and the required minimum and maximum distances for sharpness.
The application calculates optimum camera settings to minimize the combined effects of defocus blur when using too large an aperture and diffraction when using too small an opening. $2.50 from the App Store.