Optical Levels Focusing.
There is two parts to focusing on automatic levels. Focusing is very important in achieving accurate results when carrying out levelling exercises.
The first part of focusing an automatic level is to ensure that the cross hairs viewed through the telescope are clear to see and sharp. To adjust the cross hairs on an automatic level you need to place a bright coloured object in front of the telescope (I use the Yellow Chartwell Level Book) and turn the eyepiece knob until the cross hairs can be clearly seen.
The second part of focusing an automatic level is to focus on the measuring staff. This is done by first lining up the level with the staff (using the sighting collimator) and then turning the focusing knob until the staff can be clearly read.
When both of these focusing procedures have been followed you should not experience parallax. Parallax is a where a difference in the staff reading can be noted when moving the eye across the eyepiece of the automatic level.