How to setup autoguiding with the EQ6 and Meade DSI II:
Auto-Guiding simply means using another telescope and a guide camera configured parallel to the main imaging telescope to track the rotation of the earths axis accurately so stars and celestrial bodies can be imaged under long exposures without trailing. It 'locks' into a guide star which then sends signals to the mount (up, down, left, right) to the subpixel so then it can follow it.
The EQ6 mount comes standard with an autoguiding RS232 port which is only compatible with ST-4 autoguiders such as the one's made by SBIG. However, Shoestring Astronomy have created a device which emulates non ST-4 guiders with the right software. I simply use their GPUSB adapter with a Meade DSI II as a guide camera. Guide camera normally are low end budget CCD cameras just sensitive enough to see stars on the monitor. Some recommended non ST-4 guide cameras are the Phillips Toucam, Meade DSI and the Meade LPI.
You can find a list of compatible software for the Shoestring Astronomy GPUSB unit here. Since I have a Meade DSI II as the guiding camera, I use Guidestar LX200 Software Emulator v1.1a to emulate the EQ6 mount tricking it into thinking it is a LX200. Since the GPUSB unit is a USB device and that the autoguiding port RS232 is serial, you will also need Hardware Virtual Serial Port to convert the GPUSB unit.
The Meade DSI II comes standard with a set of autoguiding cable which is designed specifically for the LX200. The RS232 port on the GPUSB unit matching to the RS232 port on the EQ6 is reversed thus I had to rewire the autoguiding cable which came with the Meade DSI II. Alternatively, you can purchase this cable from Shoestring Astronomy at $6-$7 US. You can find the wiring diagram below:
The connection of the equipment are as follow:
Software Instructions:
Firstly,
open up Guidestar. Next to port, you should see a dropdown arrow, click on it
and select GPUSB then click the Start button. Ensure that you have a tick in '1
at a time per axis' box.
Now open up HW Virtual Serial Port. In the IP Address field, type your IP
Address for your computer which you are going to guide on. If you are unsure of
your IP address, go into DOS mode and type 'ipconfig'. If you are in a network
environment, enter your LAN IP for that computer eg: 10.0.0.2 . In the Port box,
type a port number which you don't use eg: 888 . Below Port Name, select a COM
port which you don't use eg: COM5. Now click 'Create COM'.
Open up Envisage with your DSI connected and
select the Telescope tab. In the 'Connect' box right below the tab, enter COM5
which you use in HW Virtual Serial Port. Click on the 'Connect' button. You
should now see in the Status box "Track Only/Guide Only" message on the bottom
of the Telescope tab. Now find yourself a guidestar on your screen. It doesn't
have to be in perfect focus. Nice round circle is good enough. Draw a red box
around your guide star about the size of your thumb nail then click 'Guide
Here/Track Here' button in the Telescope tab.
** Note: If you are using a Meade Mount to
guide, the button will display Guide Here, if you are using a non-meade
mount it will display Track Here. **
Envisage will then calculate the x and y position of your guide star. It can
take a few minutes to complete. After a while you will notice a yellow circle in
the backgound. Envisage will now move the guide star onto the centre of this
yellow circle. You are done.
All you have to do now is sit back and monitor the X and Y axis in the Status
box. If the X and Y sits on average between 0.1 - 1.5, you have good guiding.
Don't worry if the x and y axis goes up to 3 or even 5 for a few seconds. You
will not notice this if you are taking long subs.
Goodluck on your guiding adventure.