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I'm wanting to know a bit more detail about
secondary mirror sizing, 100% illumination area and what difference it all
really makes.
I'm using the program Newt. I'm building a 12.5" F5
telescope I've chosen about 2" as my focuser plus 1" free height in focuser
measurments, 14.5" ID for my upper tube so as to be able to use it as a
richfeild telescope. I'm only doing visual work, not
photography.
Punching these numbers into Newt
2.6" secondary gives a 0.6" 100% illuminated
feild.
but with a 21% obstruction..
2.14 secondary gives an almost 0" 100% illuminated
feild.
with a 17% obstruction.
What real visable difference would these two
different configurations actually give me?
Which way should I leap?
Thanks from
David Moorhouse
Auckland
New Zealand
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