The "Download Now" link directs you to the iTunes App Store, where you must continue the download process. You must have iTunes installed in order to open the link, and you must have an active iTunes account to download the application. This download may not be available in some countries.
The Underwater Photo Simulator allows you to practice adjusting f-stop, shutter speed and flash power settings to achieve a properly balanced wide angle UW photo. The program contains a 'Matrix' of actual photos made of a real UW wide-angle scene at a typical range of apertures, shutter speeds and flash power settings. You can change any of the settings and see what the result looks like. An underwater wide-angle photo has two unique exposure problems to solve. The exposure of the main subject in the foreground is controlled by the combination of f-stop and flash power. Shutter speed is not a major factor for the foreground subject. The background, however, is controlled by the combination of f-stop and shutter speed. The limited reach of the flash has relatively little effect on your background exposure. The key to a good underwater wide-angle photo is to get the foreground and background exposures to balance and look as natural as possible. The UW Photo Simulator will allow you to experiment with the settings and see the results in a real world situation. As you change any setting, the results are reflected in the UW scene displayed.