Sky and Telescope - September 2015 - 63

as premium binoculars built with the travelling amateur
astronomer in mind. These heavy-duty binoculars would
be as much at home on the deck of a battleship spotting
tiny submarine periscopes during the day as they are
under a dark, moonless night. The eyepiece ports are
mounted at a 45° angle convenient for daytime observing, and they accept most 1¼-inch-format eyepieces in
individual helical focusers, which really increase the
unit's versatility for astronomical observing. At the
Northeast Astronomy Forum last April, the company
also introduced a version of the binoculars with 90°
eyepiece holders.
The unit arrived double-boxed in custom-ﬁtting foam
with two 20-mm SWA eyepieces, along with an optional
ﬁnder bracket and a unit-power multi-reticle ﬁnder. The
last was a welcome addition, as it can be very diﬃcult to
accurately aim binoculars with eyepieces set at a 45° angle.
Lifting the unit from the box, it felt every bit as heavy as
its 14½-lb listed weight implied. It requires a heavy-duty
mount. I did most of my testing on a Manfrotto studio
tripod with a Universal Astronomics MacroStar head (universalastronomics.com) that held the Lunt 100s with ease.
The binoculars come with extendable lens shades, a
built-in carry handle, and a tripod mounting base. There
are two ¼-20 threaded sockets on either side of a 3/8-16
threaded socket supplied with a ¼-20 step-down adapter.
Given the binoculars' hefty weight, I avoided using the
step-down adapter.
Attaching the ﬁnder bracket and MacroStar L-bracket
was easy, though if you intend on standing the binoculars on the objective end, you should remove the lens
caps ﬁrst: these threaded plastic caps are convex and
don't sit ﬂat against surfaces. Aligning the ﬁnder took
just a minute or two, and I was ready to put the binoculars through some daylight tests immediately.
The Lunt 100s are virtually apochromatic - highcontrast targets in the middle of the ﬁeld show only
a hint of purple fringing, which becomes more pronounced towards the edge of the expansive 70° apparent
ﬁeld-of-view provided by the 20-mm SWA eyepieces. The
optical alignment was very good, and I had no trouble
merging the images. Viewing the siding on my neighbor's home showed some modest pincushion distortion.
The helical focusers can accommodate a wide range
of eyepieces, and their
collet-style locking
WHAT WE LIKE:
mechanisms held
Large aperture
everything in place
Unit-power ﬁnder and bracket
and centered without
any fuss. They also
Accepts 1¼-inch eyepieces
incorporate thick brass
WHAT WE DON'T LIKE:
compression rings
that won't mar your
Lens caps prone to scratching
eyepiece barrels.

The Lunt 100s include independent helical focusers that accept
most any 1¼-inch eyepieces, and their inter-ocular distance
ranges from 54 to 75 millimeters apart. Brass compression rings
keep the eyepieces tightly centered.

Under the Stars
The crisp skies of late winter and early spring provided
a wide variety of targets to really show oﬀ what is possible with what is essentially a pair of 4-inch short-focus
refractors. The Orion Nebula, M42, showed extended
nebulosity around the Trapezium, and I glimpsed hints
of its bat-like appearance on a particularly dark night.
Bright open clusters like the Pleiades ﬁlled the view with
dazzlingly bright stars and a touch of nebulosity surrounding Merope. This cluster gave me the opportunity
to evaluate the entire ﬁeld of view carefully; with the
included eyepieces, stars were nearly textbook perfect
across roughly 75% of the ﬁeld, though bright stars in
the outer 25% of the ﬁeld became elongated due to coma.
This was noticeable only on very bright stars.
Internal baﬄing in the Lunt 100s is excellent. I
observed the Moon from a thin crescent up through
full phase, and I was never bothered by ghost images
Included with
the Lunt 100s
is a pair of
SWA 20-mm
70°° eyepieces,
producing
27.5× magniﬁcation over
a generous
ﬁeld.

Sk yandTelescope.com September 2015

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Sky and Telescope - September 2015

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