Sky & Telescope - June 2022 - 70

S&T Test Report by Dennis di Cicco
Sky-Watcher's Evoguide 50DX
This new version of the Evoguide 50 has multiple uses for today's astrophotographers and observers.
tThe Sky-Watcher Evoguide 50DX package
includes everything seen here. The two-ring
mounting bracket attaches to either the green
Vixen-style dovetail and riser block (as pictured)
or the " finder " stalk at left with a dovetail
foot that fits an increasingly common quickrelease
base found on today's telescopes.
The tight-fitting, metal lens cap seen in the
foreground is a welcome feature of the scope.
and 150-mm (6-inch) long Vixen-style
dovetail bar (both are included). There's
also a small locking ring designed to
slip over 1¼-inch eyepiece barrels and
guide camera nosepieces to set the
approximate focus position as they slide
into the Evoguide's focuser.
A label attached to the Evoguide's
Sky-Watcher
Evoguide 50DX
U.S. Price: $335
Skywatcherusa.com
What We Like
Excellent optics
Solid construction
Highly versatile beyond its
calling as a guidescope
What We Don't Like
Backlash in the focusing ring
WHILE THE NAME RIGHTLY implies
that the Sky-Watcher Evoguide 50DX
was designed as a guidescope, it's more
versatile than that. Fitted with eyepieces,
it can serve as a high-quality
finder and even a small telescope (more
about that later). And with the optional
Evoguide 50ED Field Flattener ($105),
it's a decent wide-field astrograph that
performs well with sensors as large as
APS format.
The Evoguide we borrowed from
Sky-Watcher for this review still carries
the 50ED name badge on the side of the
tube, and the company says the optical
tube has not changed since its introduction
as the 50ED several years ago.
The 50DX now includes a nice two-ring
mounting bracket with soft-tipped locking
thumbscrews. This bracket attaches
to either a " finder " stalk with a dovetail
foot that fits most quick-release finder
shoes or attaches to a small riser block
70 JUNE 2022 * SKY & TELESCOPE
fixed dew shield says the two-element
objective (with one element made of
extra-low-dispersion glass) has an aperture
of 50 mm, but on the optical bench
I measured the full aperture that brings
starlight to a focus on axis as being
51 mm. That's a small, but nevertheless
welcome, difference. Slightly more
significant is the issue of the objective's
focal length. The label states it's 242
mm, while the manual calls it 250 mm.
I measured it as 253 mm, which is the
value confirmed by the scope's image
scale when shooting without the field
flattener. This makes the scope's native
focal ratio f/4.96. The field flattener
slightly increases the effective focal
length to 266 mm and f/5.22.
The Evoguide's helical focuser, which
does not rotate the drawtube when the
focus ring is turned, has a modest 18
mm range of travel. With the focuser
fully retracted, the scope's overall
length is just 22 cm (a touch over 8½
inches), and the focal point lies 65 mm
outside the mounting surface of the
drawtube's male M42 threads (often
called T threads in the camera world).
While the manual doesn't mention
it, this is enough back focus to attach
ALL IMAGES COURTESY OF THE AUTHOR

http://www.Skywatcherusa.com

Sky & Telescope - June 2022

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