Volume 2 : 3 ratio of the volumes of the sphere and cylinder is credited to Archimedes. The volume of a sphere is the integral of an infinite number of infinitesimally small circular disks of thickness "dx". The calculation for the volume of a sphere with center 0 and radius "r" is as follows. The surface area of the circular disk is formula_10. The radius of the circular disks, defined such that the x-axis cuts perpendicularly through them, is or where y or z can be taken to represent the radius of a disk at a particular x value. Using y
Four Thirds system DSLRs. The smaller flange focal distance allows for more compact normal and wide angle lenses. It also facilitates the use, with an adapter, of lenses based on other mounting systems, including many manual focus lenses from the seventies and eighties. In particular, Four Thirds lenses can be used on Micro Four Thirds bodies with an adapter, however, "all of the functions of the Micro Four Thirds System may not always be available." Four Thirds system The Four Thirds System is a standard created by Olympus and Eastman Kodak for digital single-lens reflex camera (DSLR) and mirrorless camera design and development.