To: nilsolof.carlin{at}telia.com, atm{at}shore.net
From: mdholm{at}telerama.com
Reply-To: mdholm{at}telerama.com


Nils Olof Carlin wrote:

>There might be other reasons to use a cell with more points. The
>optimum ~0.4 radius of the 3 point cell is rather small, and it
>*could* mean the load distribution between these 3 points at lower
>altitudes becomes rather skewed unless the often-neglected edge
>support is good enough

I have read statements similar to this on this list before, but I wonder if
it is true in a practical sense.  One has to build good enough lateral
support to maintain the mirror in it's centered position to a fairly close
tolerance. Without that degree of lateral support, the mirror would shift
out of collimation.  One also has to provide some front side safety stops
in any scope that may get moved about at all, or any mounting where there
is any possibility of the tube going past horizontal to a mirror up
orientation.  A sensible design will also have edge stops to prevent gross
sideways motion.  Since these are pretty much givens, doesn't that mean
there will always be enough edge support to keep the forces balanced on the
3-point flotation?

Mark Holm
mdholm{at}telerama.com

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