Quote:
Originally Posted by gary
Scopes such a the Obsession purposely come with thin mirrors so they
cool down quickly. These are then augmented with a well engineered
mirror cell and sling arrangement to keep the mirror from flexing.
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Whilst Gary has given a good description of the advantages of choosing a premium made scope over budget models, I would just like to comment on the statement above.
The obsession website states 2" thick mirrors for the 15 and 18 inch models, and "full thickness" for the 12.5" model. The marketing blurb appears to spin thick mirrors as an advantage, but modern telescope design is now more about thin mirrors which cool more quickly.
When I asked Mark Suchting to make for me a 15" diameter 2" thick mirror, he strongly suggested that I take a 1.6" thick one would cool much more quickly (40% quicker i found out from online data) and be lighter in weight. The reduced weight does however necessitate taller rocker and mirror boxes to accommodate higher mounting of the altitude bearings to achieve balance.