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I feel that I can give an informed opinion on this subject, having been
around scopes and mounts for just over 60 yrs. In most cases it is the tripod. Wooden ones are generally much less prone to vibration than
any metal ones. The situation can usually be improved significantly by'
using vibration dampers under the tripod's feet, and/or suspending a substantial weight beneath the mount. In the case of larger Newtonians,
8" and up, on EQ mounts, another factor comes into play. Frequently, the tube rings/ dovetail plate assembly is not up to the job. Regardless of the ribbed construction of the dovetail plate, there is just too much overhang each side of the saddle. For example, my HEQ5 with a
90mm f/10 refractor aboard is rock solid. Vibes from a good tap are gone in a second or less. Put my 8" on it, and the same tap results in 4 to 5
seconds of frustrating wait. I can reduce it to around 3 secs by
moving the rings 50mm closer together. You can in fact improve on that
further by moving them even closer together, but then the OTA starts to
become more vulnerable to the wind, and just starts to distort a little under it's own weight.[The same overhang problem]. A custom made deeper and heavier duty dovetail plate can almost eliminate the problem. I just fitted an electric focuser[ sheer luuuxury]. That will have to do, I've rabbited on too much already.
raymo
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