In a tacheometry survey of distance formula, the additive constant is expressed as:
1
(Focal length of objective lens) + (Distance from objective lens to vertical axis)
2
(Focal length of objective lens) - (Distance from objective lens to vertical axis)
3
(Distance from objective lens to vertical axis) / (Focal length of objective lens)
4
(Focal length of objective lens) / (Distance from objective lens to vertical axis)