Few amateur astronomers willingly abuse their telescopes. One has after all paid a high price, either in cash or in labour (if the instrument is homebuilt); one's instinct is to handle the telescope gently.

Ordinary careful usage includes such precautions as guarding against excessive accumulations of dust and moisture, and against jolts or traumas that can disturb the optical alignment. It is important to refrain from touching optical surfaces with the hands. Surprisingly, a mere touch can be one of the most damaging things you can do to a fine lens, because the sophisticated chemical coatings on modern optics are susceptible to permanent etching by the acids left behind in your fingerprints.

Dust should be removed from mirrors and lenses with soft lenstissue or a light jet from a compressed-air can designed and sold for this purpose. Optics should be cleaned as seldom as possible; a few specks of dust will harm the lens far less than a scratch that you may accidentally cause during cleaning.

Recollimation of the optics is a chore that should never have to be undertaken if your telescope is a refractor or a catadioptric of the Maksutov design. These types are noted for their relative permanence of adjustment, even if handled roughly. Newtonian reflectors and Schmidt–Cassegrain telescopes may occasionally become misaligned, especially after being transported in cars, etc. This does not represent a weakness in these instruments, for they are designed to be readjusted with great ease, as follows.