I disagree. Add slideable tube weights and it's much easier to achieve balance for changing eyepieces or cameras. The friction on the axels will take care of most of that anyway. Only if you add something as heavy as a binoviewer would you have a need for rebalancing. Sliding a tube that size and weight has risk attached to it. It's much bettter to fix the tube in place and slide a tube weight. That is a one man piece of cake operation. You don't give up any longitudinal balance. It can also be done easily with weights attached to a slidable tube ring. Or the way I have it on the Clark. BTW, the original Clark didn't have tube rings. The tube was fastened to the saddle via 4 bolts. The fact that this is up for discussion shows that tube slippage is a problem. In order to tighten the rings enough to stop splippage when pointed vertically you very well could stress the lens cell. A pin would avoid all of that. Quoting Chuck Hards <chuck.hards@gmail.com>:
Why use tube rings and then disable them with a pin? Suddenly you have lost the ability to quickly achieve longitudinal balance if using heavier or lighter than usual accessories. Admittedly, at SPOC we don't really have many (if any) members using the telescopes with any significantly massive instrumentation attached, but the option is nice. With the tube pinned, clamp rings become simply dead weight. May as well just screw the OTA to a saddle and sell the rings.
Properly shimmed (felt) rings cannot be "overtightened" anyway. A set of tube rings is too far away from the lens cell on a long refractor to introduce any unwanted stress to the cell.
On 3/15/11, ziggy943@xmission.com <ziggy943@xmission.com> wrote:
What do you mean "a band-aid?" It's a permanent solution. Never worry about slippage. Never overtighten the rings and introduce a pinch to the lens cell.
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