Major thirds tuning hand is stationary and the fingers move, each finger being responsible for one fret. Consequently, three hand-positions (covering frets 1–4, 5–8, and 9–12) partition the fingerboard of classical guitar, which has exactly 12 frets. Only two or three frets are needed for the guitar chords—major, minor, and dominant sevenths—which are emphasized in introductions to guitar-playing and to the fundamentals of music. Each major and minor chord can be played on two successive frets on three successive strings, and therefore each needs only two fingers. Other chords—seconds, fourths, sevenths, and ninths—are played on only three successive frets. For fundamental-chord fingerings, major-thirds
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.