There are two measure-up indices on a Spectra Precision Focus-30 / Focus-35 Robotic Total Station:
The lower tape hook is for ‘Slant Height’. The top dot & cross is for ‘Vertical Height’.
If you enter a ‘Slant Height’, the data collector shows you the equivalent ‘Vertical Height’:
(Sorry, the picture is faded…to the right of ‘Vertical’ there is a 5.1600) If I measure 4.650′ to the tape hook then SurvCE computes 5.160′ to optical center.
Alternatively I could select the ‘Vertical’ radio option and then enter 5.16 directly.