I almost didn't get it.
Like most jokes about the sky, that was was over my head.
On a more serious note, I have casual observed that myopia is less
common among amatuer astronomers than in the population at large.
They do spend more time focussed at infinity and with a fully expanded
pupil than do most. Maybe that has something to do with it.
: On a more serious note, I have casual observed that myopia is less
: common among amatuer astronomers than in the population at large.
: They do spend more time focussed at infinity and with a fully expanded
: pupil than do most. Maybe that has something to do with it.
More likely that they didn't have myopia to begin with. And people
that have myopia not getting into astronomy because they can't
see all that well in a scope.
-- Andy Barss
Upwards to 2% of the US population has congenital myopia.
About 20% of the population develops it between the ages of 5 and 20.
About 8% between 20 and 40.
And some develop it later.
Doubtful. A more accurate statement would probably be that about 20% of the
population is *diagnosed* between those ages. That figure undoubtedly includes
some children who are congenitally myopic, or who developed myopia during
their first five years, but were never diagnosed until their first routine
vision screenings conducted by their respective public schools. I don't
pretend to know how many children fall into that category, but I'm quite
certain the number is greater than zero.
Doug Miller (alphageek at milmac dot com)
Typically, the construction of an amateur astronomy telescope is largely a
precision woodworking project; sometimes metalworking, sometimes
ultra-precision glass grinding/polishing as well. Rather appropriate to
your part of the planet I should suspect (having previously spent 11 years
in Arizona). DAGS on ATM.
If you take a class from John Dobson or just follow his instructions,
or just build any Dobsonian mount, the woodworking and other
construction involved is hardly precision nor does it need to be.
Nowadays I am given to understand using a Dobsonian mount is by far
the norm for a amateur telescope; I know I have seen a bunch of
homemade Dobsonians but very few other kinds. Of course, that may be
because Dobson stops by in my little town (pop 8000) to teach
telescope making. He actually stays a couple houses down from me.
His whole focus is to teach how to construct a decent reflector with
commonly available materials. The only items that were purchased
specifically for the purpose in his class was the secondary reflector.
Everything else is from materials adapted to making the telescope. The
eyepiece for example was taken from a decent pair of old binoculars
purchased at a pawn shop.
And, grinding and polishing and testing and adjusting the primary
mirror, is done completely by hand and Dobson claims to get better
results that way than by using equipment to grind it. He corrected my
mirror after inspection of the diffraction pattern it produces off a
reflection from a power line insulator, by pushing around the
polishing rouge with his thumb in a circles for a few minutes.
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