Kurt, do not apologize for the Ealing posts. It's incredibly valuable information. The Ealing is by far the fussiest scope at SPOC, and I'm glad someone had the time, inclination, and technical ability to dive into it's quirks. Thank you! On Mon, Jun 16, 2008 at 8:54 PM, Canopus56 <canopus56@yahoo.com> wrote:
Third, if SLAS still has the ancient Ealing autoguider floating around, and it still works, it could be moved back to the control room. An offer could be made to Chuck to sell SLAS his contorller.
The autoguider is a dual photocell setup, each with a knife-edge cutoff and postitioned at 90-degrees to the other (one is RA, the other DEC). It takes the place of a regular eyepiece on the guidescope, and has an itegral eyepiece for visually positioning the guidestar. I have never had good luck using it with a pickoff mirror on an off-axis guider due to a lack of a suitably bright and suitably red star positioned just-right relative to the object being photographed. Also stars at the edge of the FOV of off-axis guiders are never round. It must be positioned correctly, so that the knife-edges correspond to drift in RA & DEC. It controls the drive corrector & telescope directly via 2 cables. The stock cables are probably not long enough to be used on the Ealing, they will have to be lengthened or new ones must be made-up. My preference would be a coiled cord like an old-fashioned telephone handset cord, or old headphone coiled cord. As I said, I do have two complete assemblies of this drive corrector, including the autoguiders and hand paddles for both. As to selling one...I'd have to think hard about that. I know for a fact that Patrick used to have a copy of this same unit, perhaps the Ealing drive corrector is his old one? Again, thanks Kurt. I've avoided the Ealing mostly because of it's idiosyncrasies; you've found the way to tame it.