Modification of a EQ-style Dual Axis Controller to Add an Autoguider Port The EQ-style telescope mount series are some of the most widely sold
mounts in the world. Various companies such as Celestron and Orion
sell versions of these mounts. They are all produced by Synta.
By adding on the motor and handcontroller accessories that are available for these
mounts, long-exposure manually-guided astrophotography can be performed. However,
these handcontrollers do not include autoguider ports so that computer driven
autoguiding can be utilized.
There is no standardized autoguider port that is common to all manufacturers, but the socalled
ST4 port is a very common format used on most scopes.
These instructions document a procedure that was used to modify an EQ3 dual-axis
handcontroller to add an ST4-style autoguider port. The CG-5 mount that it was attached
to was then successfully used to perform astrophotography using GuideDog software
from barkoSoftware (
www.barkosoftware.com). Guiding error was kept below +/- 4 arcseconds.
Besides your modified handcontroller and the guiding software, you will need a
suitable webcam, a computer near your telescope, a guide port interface such as model
GPINT-PT from Shoestring Astronomy, and a cable to go from the interface to the
handcontroller. Shoestring Astronomy also sells a kit with the parts you will need to
make this modification.