Mounting the long OTA [again.]

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Thursday is wet and windy so I can't open the shutters for a working light. Fortunately I have the powerful LED bulb overhead.

I need to add a counterbalance to the focuser end of the long OTA. Logic suggests something more useful than just a big lump of metal. A 50mm finder on either side of the main tube might be a good idea. Though I'd need proper rings to allow alignment with the prime instrument.

I also need to find room for the 150mm OTA for solar H-alpha. Fitting it beside the 180mm [7"] would produce a weird balance situation if the 7" was central on the saddle. Putting it on the outside of the 7" simplifies some of the balance issues but bulks it out and greatly increases the need for more counter-weighting.

Placing the OTAs side-by-side, but on extended saddle crossbars, would work. Or, I could use normal, hinged tube rings to hold both tubes closely together. Though that would be an asymmetric load unless I offset the 7" on the saddle first to compensate. The 6" could then be rotated around the 7" to achieve the optimum position.

Whereas attaching both OTAs directly to the saddle crossbars would be a non-adjustable layout. Will the tube rings for the 7" manage the weight of two heavy OTAs dangling from them! It's a thought. I bought some 8" white, hinged tube rings for my 7" and one of them cracked right across the casting at the hinge! The tiny cross sections here hadn't been given any thought by the [presumably Chinese] manufacturer. I haven't really trusted any tube ring ever since.

Then there is the matter of bringing both focusers together for ease of use and how that would affect the longitudinal balance of the pair. Both OTAs are refractors and typically nose heavy. The 6" would have an extended tail end due to the cantilevered, H-a components. Both would normally use star diagonals for comfortable viewing.

Then there is the matter of adding binoviewing and all that entails. I didn't make much progress on this due to the ridiculous magnifications involved due to the GPCs. [Glass Path Correctors.] Similar to Barlow lenses but more compact. They produce foolishly high magnifications due to their distance from the focus. A claimed 2.8 x is probably closer to 5x in actual use! With a typical refractor focal length the high magnifications demand excellent seeing. Not something which can be guaranteed!

I bought second 26mm and 32mm EPs for binoviewing. Then ended up with two very different lengths of Meade 4000 32mm. One Japanese made and the other presumably Chinese. They have a difference of about half an inch [from memory] in their eye cap lengths above the focuser. Making balancing the images a nightmare! If I buy a third 32mm [secondhand as usual] can I guarantee to get two the same? I haven't found one yet.

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