TRUE POLE ALIGNMENT of an
OBSERVATORY CLASS EQUATORIAL

1)

Collimate Optical Axis to the Tube Mechanical Axis

i) This applies to both refractors and reflectors.

ii) The reflector is at a disadvantage because a tilt of the objective displaces the optical axis.

iii) The axes need not be coincident but they must be parallel.

iv) The object glass of a refractor must be squared on and this is best done by field collimation.

v) The initial collimation of a Newtonian may be done in daylight and completed by field collimation.

vi) The mirror must not move in its cell, and the tube assembly should be very stiff.

2)

Collimate Finder

i) Use the filar micrometer to define the field centre.

ii) Select a star near the pole to reduce tracking errors.