ASTRONOMER’S WORKBENCH by Jerry Oltion
Bartol’s Beefy “BlueShift”
Here’s a mount with Go To technology designed from scratch.
MANY AMATEUR TELESCOPE MAK-
ERS have built their own equatorial
mounts. Indeed, in the days before
the Dobsonian revolution, German
equatorial mounts were the most com-
mon type for amateur telescopes. They
tended to be made from pipes and other
plumbing parts.
When Southern California amateur
Thomas Bartol made his fi rst telescope,
a 10-inch f/5.6 Newtonian in 1986, he
built a machined-aluminum equatorial
mount for it and used it to successfully
view Halley’s Comet. He also became
enamored of Jupiter and particularly its
moon shadow transits, which he hadAL
L^ PHOTOS^ BY^ TOMBART
OL72 SEPTEMBER 2019 • SKY & TELESCOPE
never heard of before witnessing one
unexpectedly.
His homemade mirror turned out
to be very good, about^11 / 2200 th wave, and
provided such excellent views that Tom
quickly felt the urge to record those
views photographically. However, even
his better-than-average mount wasn’t
stable enough for serious astrophotog-
raphy. “Though I could have purchased
one of the very good mounts available
to amateurs at the time, I’ve always
been a maker,” Tom says. “So, starting
in 1999, I began a long-term quest to
design and build my own robotic tele-
scope mount.”
Note the word “robotic” there. That’s
right: Not only did Tom decide to build
a tracking mount stable enough for
photography, he decided to computer-
ize it, too. I can count the number of
people I know who have done that on
the fi ngers of one hand, with a couple of
phalanges left over.
Tom reports, “At the outset neither
I (nor my loving and patient wife!) had
any inkling of the 18-year journey: the
friends I would make, the machine shop
I would build, the lathe I would restore,tTom Bartol’s “BlueShift”
German equatorial mount
is a wonder of design and
engineering.u(A) The mount started
out as a pile of raw steel
and bronze. (B) This rough
bronze plate became a pre-
cision worm gear. (C) The
worm gears require preci-
sion cutting to minimize
tracking errors. (D) Tom’s
fi ne machining is evident in
every part of the mount.pTom poses in the machine shop where he
built his mount.what I would learn, or how much my
passion would grow along the way (and
infect others around me!).” But he
stuck with it, and he wound up with the
gorgeous — and massive — mount you
see here.
The mount, which he calls “Blue-
Shift,” weighs in at 300 pounds. That’s
a bit much to carry around, so Tom
built a hand-cranked forklift to load the
equatorial head in and out of his vehicle
and wheel it from the vehicle to the
observing site.A