RE: ATM SWITCHING from 18" Dobs to 10"-12" SCT: COMMENTS?

["Art Russell" <artrussell@mindspring.com>]

Carl,

I currently own an 18 inch Tectron Dobsonian. At 97 pounds, I can set it up
myself in about 15 minutes (20 minutes with help) and have essentially TWICE
the mirror of a 10 inch SCT. I previously owned the Meade LX200 with
super-wedge. Set-up was typically on the order of an hour. Additionally,
don't over estimate the weight of the optical tube assembly on the fork
mounted Schmidts. One word: HEAVY. I found it much more difficult to set up
and transport the 10 inch LX200 than my 18 dobsonian.

As to optical quality. A well made Newtonian will typically outperform the
mass market SCTs as has been pointed out previously on this list in many
postings. Speaking strictly for myself, my own experience supports this as
well. Roger Clark, in "Visual Astronomy of the Deep Sky," suggests that the
ideal limiting magnitude for an 18 inch scope is about 17th magnitude, but
only 15.7 for a 10 inch scope (16.1 for a 12 inch). I have easily observed
16th magnitude globular clusters in Andromeda with the 18 inch scope, a feat
which although not impossible, is for many observers, practically impossible
in the 10 inch (see "How Faint Can You See," also by Clark, in the April,
1994, edition of Sky and Telescope, pages 106-108), due a number of factors
including not only to the difference in the mirrors' light grasp, but also
increased secondary obstruction inherent in the SCT.

My money's with the dobsonian. However, your mileage may vary.

Happy Thanksgiving!

Clear Skies!

Art Russell
Atlanta, Georgia


mailto:artrussell@mindspring.com
http://Education.gsu.edu/spehar/
Big Dobs - "Size Does Matter"

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