Quote:
Originally Posted by White Rabbit
I'm thinking of buying both as a posed to a "12 solid tube newt for more portability for camping and things. Can anyone see a problem with this? The only thing I can see that might go wrong is the tube rings putting pressure on the truss and making the scope curve a little.
Thanks
Sandy
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Hi Sandy,
Don't go there.
Truss poles can be used to replace the solid tube of a large aperture Dob
because, by calculation and design, the secondary cage is designed to be
light.
Truss pole selection is a major factor in the performance of truss pole
telescopes. Borrowing from the world of mechanical engineering, a truss
deforms under stress. The deformation is proportional to the force applied
multipled by the length of the truss cubed, and divided by the outer
diameter of the truss to the fourth power minus the inner diameter of the
truss to the fourth power.
Normally, by design, the force is the weight of the secondary cage.
If you were to somehow support the scope by the trusses, the force would
become very large, as it would include not just the weight of the secondary
but the entire primary.
The scope would not just 'curve a little'. It would curve a lot. If it didn't
mechanically and catastrophically fail under load, the bending truss would
provide terrible optical performace as the primary and secondary go out of
alignment.
There are also serious considerations with regards the primary mirror.
Though the mirrors in the LB's tend to be thicker than premium Dobs
(this is a disadvantage, since they take much longer to cool when compared to
a premium scope with a large thin mirror), the mirror support in either case
is designed for when the scope is used sitting on the ground in an Alt/Az
configuration.
Suggest you just stick to the truss pole scope and leave the massive EQ6 at
home when on the camping trip and if you are doing visual observing.
Best Regards
Gary Kopff
Managing Director
Wildcard Innovations Pty. Ltd.
20 Kilmory Place, Mount Kuring-Gai
NSW. 2080. Australia
Phone +61-2-9457-9049
Fax +61-2-9457-9593
sales@wildcard-innovations.com.au
http://www.wildcard-innovations.com.au