Sky & Telescope - August 2024 - 71

required to balance it. Part of the weight
saving is in the tube rings, which are
thinner than usual, though I found no
issues with flexure in dozens of hours of
guided astrophotos.
The telescope comes with tube rings
attached to a Vixen-standard 290-mm
dovetail bar. The top of the rings has a
210-mm handle machined with a Syntastandard
channel to accept guidescopes
- a welcome feature over the usual flat
handles tapped with just bolt holes.
In addition, the focuser has not one
but two universal finder bases, offering
plenty of options for mounting accessories
such as finderscopes and ride-along
control computers. Users shouldn't need
to buy additional mounting bars or
finder bases.
The focuser on the 120 APO is a
dual-speed, rack-and-pinion design
that proved smooth and precise. Under
the heavy load of a star diagonal and
big Tele Vue 41-mm Panoptic eyepiece,
the combination didn't creep out of
focus or slip even when unlocked with
the scope aimed straight up. However, I
did have to tighten one of the bearingadjustment
hex screws on the focuser
very slightly to improve the tension
to prevent any slippage. Locking the
focuser still allowed adjustments with
Left: The scope's 120-mm (4.7-inch) triplet objective is anti-reflection coated. Its tube interior is
fully blackened with a ribbed section in the upper portion and three field stops all working together
to produce good suppression of stray light. Right: The 9-inch-long dew cap retracts onto the tube
but extends beyond the lens by 4 inches. It has a locking knob to secure it firmly in position.
the 10:1 fine focus knob, and I never
found it slipped over long exposure
sequences.
The focuser has a rear rotator convenient
for both visual and photographic
use. It has a scale marked in onedegree
increments, useful for repeating
the framing of images over multiple
nights. I would have liked more than
one index mark, as the single mark
located near the rotator's lock knob is
hard to see in some orientations. Also,
the knob never completely locks the
rotator. With a heavy eyepiece or binocular
viewer off to one side, I found
the rotator would still slowly turn
on its own. I never encountered that
problem with a camera attached, nor
did rotating the camera cause a shift
in focus. A warning: The rotator knob
comes off with just a couple of turns
and could drop into the snow or grass,
never to be seen again!
An attractive feature of the 120
APO is its ability to work with binocular
viewers, despite the long back focus
requirements of the accessory's complex
light path. The scope accomplishes
this by having a 4-inch-long rear tube
segment that unscrews, allowing the
focuser to be reattached onto the nowshortened
main tube.
The bottom Vixen-standard dovetail bar is
drilled with numerous holes for adjusting the
ring spacing if desired. The rack-and-pinion
focuser has a lock knob, tension screws, and
M4-threaded holes for attaching electronic
focusers.
The slotted top plate accepts accessories
with Synta-standard dovetail feet. The back of
the tube has two additional finder bases. The
3.3-inch focuser offers 100 mm of travel and
has graduated scales for focus position and
rotation angle.
Top: Removing the rear section of the main
tube allows binocular viewers (a Baader unit
is shown) to reach focus without needing a
Barlow lens. Bottom: The extension tube is required
for either of the photographic flatteners
to reach focus.
sk yand tele scope .o r g * AUGUST 2024 71

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