Quote:
Originally Posted by acropolite
Along with the others I'm concerned with the rigidity of the parallel struts, only the stiffness of the struts and mounting will prevent twisting of the upper secondary/viewfinder, although some descretely placed bracing (wires perhaps) to give some triangulation would fix that.
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I wouldn't be concerned.
Many years ago I built a 13.1inch dob with 4 struts - I was rubbished by the "experts" from one particularily large southern astro club who will remain nameless.
I did not have any problems with moving collimation. The scope was fine all all positions.
It is all about how robust the design, as has been amply discovered by these people:
http://www.ultralightscopes.com/Products.htm
based on this article:
http://www.ultralightscopes.com/atmj_article.htm
The design is simple, it is easy, and it appears to work without bracing.