The micrometer reticle is usually installed on the right eyepiece focal plane of the telescope. It is a thin surface of a polar surface that engraved the thin glass. The thin glass also participates in the imaging in theory, prolongs the focal length of the objective lens, and will have more or less influence on the length of the right eyepiece.
Verifiable resolution and optical transfer function
micrometer Reticle high requirements for cleanliness, any tiny dust could have large black spots in the observation, and the precision of the installation position of the reticle is extremely demanding, therefore, do not try to disassemble, if removed, must follow the original restoration.