I bought an extra-long dovetail bar and attached my guidescope to the underside of it, in front of the mount. That moved the guide scope almost directly in line with the polar shaft, and saved a lot of weight/torque. I moved the scope (Newtonian) back in its rings to help with the balance in Dec. My guidescope is the Orion 80mm one, with the SSAG.

James, I enjoy your videos very much. You take the hobby to a whole new level of science and areas of inquiry. Please keep producing these sorts of videos. They are very informative and great food for thought and understanding.

@Aero19612

7 жыл бұрын

Thanks for watching! This is a very deep hobby and you can pursue many different threads...and who knows, maybe even get a decent picture from time to time.

@aerofart

7 жыл бұрын

James Lamb indeed! :)

Just came upon this brilliant video. I was also having quite a bit of difficulty balancing the Mount. I felt that the scope would be heavy and start to rotate but then we get to a point where the weights on the shaft took more of an affect. I realize now that it has to do with the moment of inertia. Clearly the center of mass below the RA line should be the same as the center of mass above the RA line. This is easier with more than one weight which can be adjusted separately so that the center of their mass is much closer to the proper moment of inertia.This would create a system where the whole thing rotates around that line equally. Another problem is the differential weight on the right and left side of the OTA itself. I have a power box and a usb hub taped to the side of the OTA and once the clutches are opened the tube starts to freely rotate I noticed that there’s an initial movement to the heavier side but then the weights on the shaft compensate. Clearly balancing the OTA tube both right and left of the saddle would also be beneficial. I also have the CGX and stiction is quite a problem. I also went to an OAG with the 174MM mini. I’ve never had a problem with stars. This is a fantastic camera.

@Aero19612

4 жыл бұрын

Haha. The “oldies”. That’s the analysis that led me to buy the Celestron OAG. Then, after 2 years in the box, the ZWO ASI174 with its high sensitivity, large sensor, and large pixels is what made me actually start using the OAG. I’m a big fan of the 174-great guide camera. Thanks for dipping into the “ancient” video vault!

Very interesting take on things. Definitely something to consider. The things we do when waiting for our gear to come back. My mount’s sitting in customs right now haha.

@Aero19612

5 жыл бұрын

Thanks for watching, Sam! I'm very interested in identifying issues that actually are important versus those that are assumed to be important. This hobby has A LOT of issues.

Hello James. Very interesting video. I think we were both watching same recent topic on The Astro Imaging Channel. I just recently had to get an extension bar for my counterweight set up, and was slightly depressed when I saw said video! But now I see it might not make such a huge difference how close counterweights are to axis. this hobby seems to consist of continuous trade offs! great videos. Thanks.

@Aero19612

8 жыл бұрын

Thanks. Yes, it was the Astro Imaging Channel--couldn't remember that when I was making the vid. They also commented on vibration issues. I deleted that from my video due to length. I had placed accelerometers on the mount about a year ago (I'm a structural dynamicist) to measure self-induced (motors) vibration. I saw no evidence of counterweight arm vibration (and no problem with motor-induced vibration). If you start seeing odd oscillations in your RA guiding plot around 2 to 4 Hz, check back in with me with specifics of your setup--but probably won't be an issue either. This hobby is all about trade-offs and evaluating advice based on one setup that might not apply to a different setup. It's a wonder we're able to get any pictures at all.

put a weight in the middle of the mount center the weight on the a frame will help also

James, great topic and look forward to all of your videos. Regarding your guide scope, would it be possible to design a bracket to mount the scope to the counterweight shaft? I have not seen this attempted anywhere but I could be wrong - it probably opens up a host of other issues.

@Aero19612

7 жыл бұрын

Thanks for watching, Brian! That would be awesome to mount the guide scope below the RA axis--it would reduce weight/inertia significantly. The problem with current mounts is that the guide scope would have to be attached far down the counterweight bar. There are two problems: (1) clearance between the scope and tripod legs, (2) flexibility of the shaft would make it impossible to guide accurately.

it helps with balance but not really with tracking it varies across mounts having a well setup mount is important first c gem and vx mounts are always failing on the ra and dec motors KZread is full of those reports

Hi James, as I wait for clear skies, which seem increasingly rare, I am pondering the benefit of swapping out my 5 pound counterweight that is positioned at end of the shaft with a 10 pound weight that I would position farther up the shaft. After watching your video the decision should be a no-brainer, but in my case I do not use guiding software to command my mount to make minor adjustments. My mount is German Equatorial but it is also 45 years old, so I don't have modern accoutrements. For astrophotography I completely rely on precise polar alignment, a synchronous RA motor, and a little luck to acquire subframes from 30 seconds to 300 seconds in duration. So back to my question, since I am running the clock drive at a constant rate, is there any benefit to using a different counterweight?

@Aero19612

7 жыл бұрын

Hey Brian. I doubt there is any benefit, particularly for a constant-rate system like you have. Even for an autoguiding system that sends commands to "slow down" and "speed up" to the RA motor, there is probably not much benefit unless the payload weight is at the limit.

Very interesting. Thank you. Question, can stiction be zero or close to zero on a ioptron Z mount where the weight is directly over the center of gravity? They swing like a pendulum when properly balanced.

@Aero19612

6 жыл бұрын

Stiction can never be truly 0; however, it can be small enough that you don't really notice it. My CGEM had very noticeable stiction when I first got it, but after it was hypertuned, the stiction is much much less.

yeah but you only really use RA i see what you mean counterbalance for the torque weight does improve to a point but its minimal i am sure even if you did over balance it it would just create more backlash and probably put you out 1 arch degree a second

sorry bro but you cannot stop the world from turning dont forget that in the equation