4. Fine leveling(spirit level tool)
is to make the line of sight of the telescope accurate and level. A set of prisms is installed on the upper part of the level tube to refract both ends of the bubble of the level tube into the level observation window next to the mirror tube. If the bubble is centered, the images at both ends of the bubble will conform to a parabola, indicating that the line of sight is horizontal. If the images at both ends of the bubble do not match, the line of sight is not horizontal. At this time, the micro tilt screw can be rotated with the right hand to make the images at both ends of the bubble fully meet the requirements, and the instrument can provide a horizontal line of sight to meet the requirements of the basic principle of leveling. Note: the moving direction of the left half of the bubble is always inconsistent with the direction of the right thumb.
5. Cut off the reading on the spirit level tool with crosshair(spirit level tool)
. The spirit level tool is mostly inverted telescope, and the reading shall be carried out from top to bottom. First estimate the millimeter reading, and then report all the readings. Note that the use steps of the level must be carried out in the above order and cannot be reversed. In particular, the bubble adjustment before reading must be carried out before reading.(spirit level tool)