Sky & Telescope - June 2024 - 74

ASTRONOMER'S WORKBENCH by Jerry Oltion
Almost all the components are 3D
Make a Little Magic
Catch field-of-view fever with this beautiful binocular scope.
Robert Asumendi's Magic binoculars are
compact and versatile, and they will knock your
socks off with their wide field of view.
ROBERT ASUMENDI IS arguably the
most vocal proponent of binocular
astronomy these days. I've written
about his 8-inch (200-mm) " Drifter "
binoscope (S&T: June 2019, p. 74) and
his 80-mm " Heart " (S&T: Aug. 2022,
p. 72), but Robert hasn't been resting
on his laurels. For the last couple of
years he's been working on yet another
design, this one a 50-mm f/3.6 version
that he calls " Magic. "
You'll notice that the aperture keeps
going down. That's contrary to most
people's experience when they get into
amateur astronomy. The most common
affliction among us is " aperture fever, "
wherein we seek out larger and larger
optics, but that comes at a price: The
field of view shrinks. Robert went the
other way, pushing the limits of how
wide he could go with the view rather
than with the aperture.
That limit is surprisingly wide. No,
it's astonishingly wide. Looking through
Magic is like nothing I've experienced
before. At its lowest power, with a pair
of 36-mm eyepieces, Magic delivers 14°
of glorious cosmos. That's enough to see
entire constellations at once.
If you do the math, you'll see that
the exit pupil with those eyepieces is
10 mm, way bigger than the 7 mm
74 JUNE 2024 * SKY & TELESCOPE
that most people's eyes will accommodate.
Are you wasting light? One look
through the Magic will show you that
you're getting plenty of photons. A 14°
field of view is nothing short of spectacular
even if you're not using all of the
light that enters the objective. As Robert
points out, " Using eyepieces with an
oversized exit pupil gives you a free pair
of 42-mm binoculars, a pair of 35s, 30s,
and even 24s inside Magic. "
Going the other way, Magic will
easily handle 75× if you use highquality
lenses and diagonal mirrors.
That's enough to see a ton of detail on
the Moon, Saturn's rings, and Jupiter's
bands as well as bust open star clusters
all the way to their cores.
As with Robert's Heart design,
the Magic binos are designed to look
downward into, so you can use them
comfortably while they're aimed up
into the sky. They're great for hand-held
exploration, but they can also be tripod
mounted, which becomes essential
beyond 15× or so.
Reverse aperture fever:
Robert's 8-inch (200-mm)
Drifter, his 80-mm Heart, and
his 50-mm Magic binoculars
progress smaller in aperture
but wider in field of view.
printed. One advantage of this is the
flexibility it allows ATMs to tweak the
design to their own liking. Robert has
even experimented with longer-focalratio
objectives, simply extending the
body to accommodate the increased
light path.
The real attraction, though, in my
opinion, is the extra-wide view of the
night sky with the short-focal-ratio
lenses. I go out observing with Robert
fairly often, and night after night he'll
call me over to his scope with a " Hey,
cool, look at this! " I'll take a peek and
see the Double Cluster with the Muscle
Man (Stock 2) in the same field, or the
entire Cygnus Loop (the Veil Nebula)
with room to spare all around it.
The Cygnus Loop in 50-mm binoculars?
You'd better believe it. Because
Magic can also use regular eyepiece filters
in cartridges that slide in directly
below the eyepieces. With a pair of
O III filters in place, practically every
nebula in the sky looks as glorious in
Magic as it would in a 10-inch Dob.
It's just smaller, which means more
context. The Cocoon Nebula (IC 5146)
is one of my favorites: You can see not
only the emission nebula, but the long
trail of dark nebula (Barnard 168)
stretching out behind it. The entire
thing, with room to spare. I've never
ALL IMAEGS COURTESY OF THE AUTHOR
Sky & Telescope - June 2024

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