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I am sorry to ask. But what is rotating tube assembly? I tried to find out what it is and I cannot find it anywhere who sells it.

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My solution has been to use the standard felt-lined "rings", and to polish the scope's tube with a quality carnuba auto wax. This way it i can leave the rings clamped just tight enough to hold it from moving/sliding- yet with a slight torque i can smoothly twist the tube so that the focuser is precisely where i want it!

In like manner, i can also scootch the tube fore or aft, to help balance for a particularly heavy EP, or such.

You can dial in the preferred holding grip on the "rings" by tightening/loosening the thumb-screws that hold the ring halves together, like a clamp. For me, i leave the scope in its "rings" & dovetail rail, all as a unit. Then i simply install the dovetail into the receiver slot on the mount- and am then ready to observe. So the ring's tension/grip on the tube is seldom fiddled with!

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I like the simplicity of that. I've gotta ask, though, what diameter tube, and how heavy is it? This solution works for you even when looking at the zenith?

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My solution has been to use the standard felt-lined "rings", and to polish the scope's tube with a quality carnuba auto wax. This way it i can leave the rings clamped just tight enough to hold it from moving/sliding- yet with a slight torque i can smoothly twist the tube so that the focuser is precisely where i want it!

In like manner, i can also scootch the tube fore or aft, to help balance for a particularly heavy EP, or such.

You can dial in the preferred holding grip on the "rings" by tightening/loosening the thumb-screws that hold the ring halves together, like a clamp. For me, i leave the scope in its "rings" & dovetail rail, all as a unit. Then i simply install the dovetail into the receiver slot on the mount- and am then ready to observe. So the ring's tension/grip on the tube is seldom fiddled with!

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I like the simplicity of that. I've gotta ask, though, what diameter tube, and how heavy is it? This solution works for you even when looking at the zenith?

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I ,too, just loosen the clamps and let the felt slip.And good quality car wax helps the exterior of my scope tubes look a little nicer and shed dew.

Another rotating "tool" is a big rubber ring fastened tightly around the Newton tube towards the higher end,so that the tube can't slip thru the loosened clamps and fall to the ground. It also acts as a large bearing surface against the uppermost tube clamp.In my case,this is a 30 pound 10" Schmidt-Newtonian optical tube.

If you do imaging keep the tube fixed but for visual rotating the tube sure beats standing on your head to see.

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That is a very short tube and should service you well on a GEM mount.

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Very short? Mine's a 6" F8... the tube is ~52 inches long! The only thing that keeps such a long moment-arm steady on the 'SVP' mount (rated for 20#) is the OTA's relatively light weight. Let's hear it for 1960's fiberglass!

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In my case, this is a 30 pound 10" Schmidt-Newtonian optical tube.

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Now THAT's an OTA! Slip-sliding there would be a bit trickier... can easily see where that rubber-ring would see action! Nice idea.

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Anything to increase the ease of use helps.

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That's it... once you've made the initial investment, felt the pinch, you'll have YEARS to forget about that one-time "pinch"... and every time you observe you'll thank yourself as you enjoy use of the entire scope, unencumbered- thanks to such an investment!

This, opposed to the "sweetness of cheapness" slogan.

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Anything to increase the ease of use helps.

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That's it... once you've made the initial investment, felt the pinch, you'll have YEARS to forget about that one-time "pinch"... and every time you observe you'll thank yourself as you enjoy use of the entire scope, unencumbered- thanks to such an investment!

This, opposed to the "sweetness of cheapness" slogan.

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To each his own, and I've got mine.

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There are issues with the rotation of the tube when mounted on a goto mount. Unless the tube construction is so exact that the mechanical axis of the tube is axial with the primary mirror axis when perfectly collimated, there will be a type of cone error introduced whenever the tube is rotated after the alignment has been completed.

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That's a very good point... hadn't thot of that angle. My 'SVP' isn't a "GoTo" mount, so isn't an issue there.

A similar consequence has been attributed to Newts with a rotating tube-end... attempting to achieve the same, comfortable EP positioning. Except there it's potential for collimation shift- yet due to the same mechanical issues you've described.

I've also seen & used a large (30" observatory) Newt with a rotating secondary, having FOUR detente positions at 90* around the upper tube- each with it's own focuser. I've always wondered about the collimation accuracy with such an arrangement...

Personally, i'd take the rings... let the GoTo be, at worse, a "GoNear" system... otherwise maintain collimation & comfort. Heck- my primary scope is a wooden Dob- the DSCs sometimes entail a bit of hunt-'n-peek at the end, anyway.

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