Optical Level
Purpose
The optical level is a line of sight instrument which requires manually adjusting as opposed to an automatic level which has an internal compensator mechanism which automatically adjusts the line of sight.
This equipment can establish or verify points on the same horizontal plane, you can also work out the distance by using the graduated marks inside the telescope.
This versatile piece of equipment is cheaper than a theodolite and easier to master and use for several tasks like setting out, landscaping and transferring levels.
The Optical Level
A telescope which can be extremely accurately set so it is horizontal, has a set of cross-hairs, and can be turned through 360 horizontally.
The Graduated Staff
Graduated Staff is usually made out of sections which can expand up to 4m in height.
Optical Level are used in conjunction with the graduated staff rod, the face of the rod displays small black and red 10mm squares which are spaced out by 10mm.
The design also incorporates several squares forming a letter E facing backwards or reversed containing 3 x 10mm squares either in black or red with a 10mm space in between total measurement 50mm see illustration.
The Tripod
A fully adjustable 3-legged stand on which the level sits, so that the level: is roughly horizontal, prior to fine adjustment; is at a height at which the user can see through it easily.
An Optical Level uses line of sight, albeit enhanced somewhat via the telescope, while a laser level emits a visible beam.
To get any useful information requires you to gather the correct measurements and interpret the measurements correctly.
Automatic Level
