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Thanks Maurice (and everyone else!). For a while I had problems shooting near the terminator as my secondary was badly in need of recoating (like the primary). I had much scattered light and couldn't get a black sky at the terminator. I opted for a replacement from the corroded 3.1 inch to a smaller 2.7 inch rather than realuminizing. I do occasionally shoot with higher sun angle but I'm interested in finding new lunar domes and in characterizing their slope, and this is best done at the terminator.
I refurbished my DS-16 mount since I had it for a long time. I get attached to things and couldn't bear to sell, discard or mothball it. I'm not using the original drive. I had to buy DC motors, make a pulse-width modulator to regulate speed, and learn how a parallel port works so that I could make it interface to a computer for webcam-based guiding. For the DEC I made a tangent arm assembly (since I didn't want to buy a worm-gear) so that makes it unsuitable for any GOTO abilities at the moment. For the RA, I initially used a unipolar stepper motor but found it resonated at sidereal rate (what a coincidence!) so replaced it with the same brand of DC motor used by Celestron.
The alt-az drives for dobs are really worth their money. I wouldn't recommend a DS-16 mount for anyone (they're discontinued anyway). But they do have a cult following.
I'll post some pics of my gear soon.
Zac
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