Anyone own the Explore Scientific n208CF astrograph or similar Newtonian? I recently upgraded to a CGX-L and am having a really hard time keeping balance. I can balance RA just fine, but DEC is only balancing in the horizontal position. I lose balance pretty quickly once in a more vertical position, you know like where the sky is... The imbalance is more pronounced when OTA is pointing East.
I do rotate the OTA so the camera and guide scope are inward, toward the center of mass. However, because of the saddle's size, I can only move the dovetail or the OTA in the rings so far before the focuser or guide camera/scope bump against the saddle or saddle knobs.
A couple solutions I am going to try;
1. get a longer dovetail. Moving from ~8" V to 14" Losmandy dovetail. Should hopefully give more flexibility in OTA placement.
2. move the guide scope and camera to the top of the OTA, away from the center of mass but free from the saddle/knob obstruction. There is a handle on the OTA with a 1/4-20 screw slot, so I could try to find a guide scope mounting shoe that fits over the handle, but no luck yet at least from Amazon. I guess I could also replace the handle with a mounting plate, and sacrifice a little ergonomics.
Am I on the right path to correcting balance? If anyone else has any ideas I'm all ears.
Thanks and clear skies,
*I can take pictures when I get setup later this evening.
I also have the E. S. N208CF and have encountered similar difficulties.
In my case, it's because I'm on an iOptron CEM40 mount, which has their "Z-shaped" configuration, that is, the DEC axis is offset to the opposite side of the mount from the counterweight shaft. What that means is that the OTA is shifted rearward, so that I risk the focuser and camera bashing into the mount head as the DEC crosses the zenith.
In my case I solve this with your Solution #2: I keep the focuser and camera on the far side of the OTA from the mount. This has the obvious disadvantage of moving the combined center of mass of the OTA and camera farther from the RA axis, so I have to move the counterweights farther or add more weight to compensate. That's not a huge deal, since I'm still well under the payload capacity for my mount, but the greater moment of inertia isn't ideal.
So far I haven't delved into guiding, but when I do I anticipate attaching a dovetail plate to the OTA handle and then mounting the guide scope to that. I'm pretty sure I've seen examples of that on other Exp. Sci. scopes.
EDIT: I forgot to respond to your report that your OTA is balanced only when it's horizontal. That sounds like the combined center of mass of your OTA, focuser/optics, and finder is either directly above or directly below the DEC axis when the OTA is horizontal. If you move the OTA away from horizontal and it continues moving away - especially if it does this in either direction - then the C-O-M is above the axis. If it tends to move back toward horizontal, then the C-O-M is below the axis.
In either case, the solution is to rotate the OTA in its rings to bring the C-O-M closer to the DEC axis. This usually (for me, anyway) means rotating it so that the focuser is slightly to one side and finder is on the other side. They're the only parts that contribute to the C-O-M being off the axis of the OTA, so getting them balanced is the trick.
Edited by belliott4488, 23 June 2021 - 11:36 AM.