A measuring staff (10) has a upper section (11) including a first elongated member (12) which can carry in a fixed position therealong a laser detector of a laser leveling system or a sighting marker of an optical measuring system, and a second elongated member (13) telescopically extendable and retractable relative to the first member (12), a graduated scale (18) on the first member (13) and a pointer (17) on the second member which indicates the extension or retraction of the second member (13) relative to the first member (12), a spring (20) for urging the second member (13) outwardly from the first member (11), the second member (13) being selectively lockable to the first member, and an extension section (14,15) at the lower end of the upper section and extendable therefrom.