Re: HOMEYER CRADLE REPLICA
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thanks for this Frank, you have confirmed my thoughts about OAG and SCTs. I use feathertouch and microtouch for focus control, so OAG is probably my only option.
Interesting mods you've done and I can se they'd be really helpful. Paul
On Mon, 8 Feb 2021 at 05:23, Frank S Barnes III < SBarnes@...> wrote: Hi Paul,
Due to the design of an SCT, stabilizing the mirror is a complicated task. you can't "lock" the mirror, but you can do some things that will minimize the shift as it tracks from east to west. My C14 has been modified to address the shift created by the gap between the baffle tube and the draw tube. The mirror can also shift on the mirror mount itself and you cannot tighten the spanner nut enough to eliminate it without deforming the mirror, so modification #2 addressed applying pressure to the outer edges of the mirror in 3 locations to hold it steady. And the third modification was the addition of longer bolts to replace the transfer bolts that hold the mirror during shipment. Those bolts are too short to reach the mirror support once the mirror has be brought close to focus. This requires an external focuser since once all the stabilization is done, the mirror is basically fixed. These mods allowed me to use a guidescope with pretty good success. However, the best approach is as you suggest, use an OAG and separate guide camera. A good rotator is worth its weight in gold if guidestars are sparse and only found in one orientation.
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