I've never been thrilled with my SBS balance. I don't lose sleep over it but it's just not quite right. I'm wondering if anyone has a better method. I have a C8 and WO80 on an ADM SBS plate. I balance the dec with the counterweights and then, with the dec axis horizontal and the OTAs horizontal, slide the OTAs a bit to get balance in that orientation. I first mark the balance points of each OTA and center those marks over the center of the SBS plate. That is my starting point and I adjust a little to get balance. Then, I point OTAs straight up and move the SBS bar left or right to get balance in that orientation. This static balance is then spot on. But, in other orientations, balance is a little off. Am I missing something?
Posted 24 January 2020 - 04:39 PM
With SBS, your balancing three axes instead of two. Also, things like a finderscope or off-center accessory really affects balance.
The tubes will balance on one side of the mount, but not on the other. Yes. frustrating.
I just get as close as I can. Luckily my gear train is no where near the limit of my mount. So I have wiggle room.
Posted 24 January 2020 - 06:05 PM
Astro-Physics used to have a document describing this, but I couldn't find it. So here it is from memory:
1. Assemble scope 1 with everything you will use on it (camera, finder, dovetail etc). Using a small dowel rod find the balance point of the scope (front to back). Mark the dovetail at this balance point.
2. Repeat step 1 with scope 2.
3. Put both scopes on the side by side dovetail saddles, with the center balance point of each scope marked above in the center of the long arm of the SBS dovetail (or the center of the saddle). If this is done correctly the center of the long arm of the SBS dovetail should also be the balance point front to back with both scope loaded on it.
4. Now put the dowel rod under the long arm of the SBS dovetail, so that the dowel rod is parallel with both scopes. The side to side balance will be somewhere in between the scopes. Mark that balance point.
5. Remove the scopes from SBS saddles.
6. Put the SBS dovetail and saddles on the mount, such that the balance point of the SBS long arm is in the center of the mount head.
7. Put each scope back in the saddle and center the marked balance point in the center of the saddle.
This should be very close to balanced, and since you marked everything it is repeatable even if you remove the scopes each night.
- elfuma and RossW like this