Hi,

I have had a DSI Pro ccd camera for some time, but haven't had the time to try it out until this weekend. I was taking some unguided images of Jupiter with my C8 and decided to try building a RA axis autoguider for the C8. I had a spare Meade 492 motor and it only took a couple of hours to fabricate a simple system that sits inside the forks and rotates the RA adjustment knob. Below are a couple of photos of the prototype. This sytem seems to work pretty well. The Autostar motor can rotate the RA adjustment knob and move the telescope. There is a fair bit of backlash in this adjustment knob and this system wouldn't work for full goto operation, but for autoguiding it may be OK. A rough test with a guiding program and my webcam shows that the autoguider will drive the Autostar system. I need to adjust the friction wheel that contacts the C8 RA knob and will probably add a small belt or rubber strap for better contact and to reduce torque on the worm wheel axis. Otherwise the prototype works very well for only a 3 hour project, and was a pretty simple and quick way to add autoguiding (RA axis only) to an older SCT.

Bill

Hi,

I had to modify the original autoguider design to remove the little friction wheel that turned the RA adjustment knob. Unfortunately the friction wheel required a small amount of pressure to give a good contact and this negatively affected the Autostar motor, giving drive and unbalanced load error messages. I replaced the friction wheel with a small cup, that fits directly over the RA adjustment knob. I filled the cup with hot glue and molded it to the RA knob. It easily pops down over the RA knob and grips very well. The entire assembly is mounted on a nylon kitchen cutting board and just slips inside the forks. The cutting board can slide parallel to the declination axis within the forks, and the motor can slide perpendicular to the forks; it sits within two aluminum rails and is held to the cutting board with strong elastic cord. The sliding motor assembly allows alignment of the worm wheel axis with the C8 RA adjustment knob axis. The autoguider system just slips into place inside the forks and is easily removed, keeping the C8 in an original-unmodified condition. I plan to construct a similar autoguider to turn the Dec axis fine adjustment knob (another rainy day project). Below is a photo of the final system and I will ASAP update my webpages with complete construction details.

Bill