Leveling a Level

To function accurately, the level must provide a perfectly horizontal line of sight in any direction you train the telescope. To ensure this, you must level the instrument as discussed in the next paragraphs.

When you first set up the tripod and instrument, make the footplate as nearly level as possible.

1. Train the telescope over a pair of diagonally opposite leveling screws, and clamp it in that position.
2. Manipulate the leveling thumbscrews, as shown in Figure 5-17, to bring the bubble in the level vial exactly into the marked center position. Manipulate the thumbscrews by simultaneously turning them in opposite directions. This shortens one spider leg, the threaded member running through the thumbscrew, while it lengthens the other. It is helpful to remember that the level vial bubble will move in the same direction that your left thumb moves while you rotate the thumbscrews. In other words, when your left thumb pushes the thumbscrew clockwise, the bubble will move towards your left hand; when you turn the left thumbscrew counterclockwise, the bubble moves toward your right hand.
3. After leveling the telescope over one pair of screws, train it over the other pair and repeat the process. As a check, set the telescope in all four possible positions and be sure that the bubble centers exactly in each.

Various techniques for using the level will develop with experience. In this section, we will discuss only the techniques we believe essential to the Builder rating.