ZoneCam

This app is designed to learn about and explore the characteristics of tonal rendition and resolution in digital photography. The process starts with the basics of Ansel Adam's Zone System in comparing a standard camera view with the averaged samples of the 0 to 10 tonal zones at various levels of resolution (using the slider). The tonal scale itself is also adjustable with the Pixel Mode menu to an 8 bit image (256 levels of gray or color). For example, with a 100 unit-8 bit gray setting, one can see the image quality produced by the first digital camera prototyped at Eastman Kodak Labs in 1975.
Other features using the topleft menu include switching the camera from front to back and capturing a screenshot to your cameraroll. Also, click the camera image to freeze it, and click the lower image to show the zone/gray value of the point touched.
Given Ansel Adam's life-long interest in translating the world's image in simple and elegant shades of gray, I think he would have enjoyed using this app as a tool for visualizing nature along with his view camera and spot meter.