Australian Sky & Telescope - April 2018

SCOPE MAINTENANCE by Rod Mollise

SEAN WALKER /

S&T

Follow these steps to

get your telescope into

perfect alignment.

THE VERSATILE AND PORTABLE SCHMIDT-CASSEGRAIN

telescope is without question among the most popular type

of commercial telescopes ever sold. However, some amateur

astronomers don’t respect the SCT, regarding it as an also-

ran optically compared to other designs. The fact is, SCTs

are better telescopes than observers often acknowledge. At

least they can be, if properly collimated by ensuring that the

telescope’s large primary and smaller secondary mirrors are

properly aligned. Unfortunately, many of the SCTs I encounter

are out of collimation, and yet the owners are sometimes

afraid to adjust their telescopes’ optics. The idea of collimating

a complicated-looking telescope is admittedly scary, but there’s

really nothing to fear. The SCT is actually easier to collimate

than any other design. Only one optical element needs to be,

or can be, adjusted: the secondary mirror.

W COLLIMATION

TEAM Getting your

Schmidt-Cassegrain

telescope in perfect

optical alignment

can be quick and

easy, particularly if

you have a friend

to adjust the

screws while

you monitor the

progress at the

eyepiece.

Collimating a

Schmidt-Cassegrain

62 AUSTRALIAN SKY & TELESCOPE April 2018