Starlight Xpress Lodestar guider - Manual (Page 3)

Lodestar handbook Issue 1 September 2007
lenses cannot fully illuminate a half-inch format CCD, so take care when selecting a lens for this
purpose.
A typical set up might consist of an inexpensive 80mm F5 refractor ‘piggybacked’ onto an SCT, with
the Lodestar fitted directly into its focus barrel. Many such telescopes are designed to be used with an
inverting prism ahead of the eyepiece and so the focuser may be too short when the Lodestar is inserted
directly. In this case, an extension tube may often be made from a cheap Barlow lens assembly with the
lens removed. This configuration can be seen in the picture below.
The Lodestar attached to an 80mm F5 guide ‘scope
The focal length of your guide telescope is not especially critical for good guiding, as the guiding
software searches for the ‘centroid’ of the guide star image and can resolve shifts of far less than 1
pixel. Using a guide scope with a relatively short focal length (between 300 and 500mm) makes guide
star finding very easy and this is a recommended setup for general purpose guiding.