What part of a telescope is adjusted to ensure precise sighting?

The part of the telescope that is commonly adjusted to ensure precise sighting is the cross hairs. Cross hairs are fine lines that create an aiming point in the viewing field. They help the user align the telescope accurately with the target being observed, allowing for precise measurements and sighting.

When aiming a telescope, it is essential to have a clear and exact reference point, which the cross hairs provide. By aligning the target with the cross hairs, surveyors can obtain accurate readings and measurements. Adjusting the positioning and clarity of the cross hairs is fundamental to achieving reliable and repeatable results in surveying tasks.

Other components like the objective lens, diopter setting, and focusing knob are important for overall clarity and focus of the image seen through the telescope, but they do not specifically enhance the sighting accuracy in the same way that the cross hairs do. The objective lens gathers light and forms the image, the diopter setting is used to correct for differences in vision between the observer's eyes, and the focusing knob adjusts the clarity of the view but does not provide the aiming precision that cross hairs do.