Serious Amateurs will Love the SW 120mm ED-APO Refractor
Sky-Watcher high-performance ED-APO refractors offer premium optical
performance for the discriminating amateur astronomer. Refractors are
coveted for their superb contrast, high-definition, and coal-black sky
background that make stars appear like diamonds imbedded in black
velvet. SW APO refractors utilize the most modern optical glasses and
fabricating techniques to deliver the ultimate in high-fidelity
astronomical imaging. Subtle details pop as never seen before in
telescopes of lesser optical capability.
Observing with the Sky-Watcher PRO 120ED APO Refractor
The additional aperture compared to a 100mm diameter lens provides a
dramatic increase in resolution and a heighten sense of seeing lunar
and planetary surface phenomenon in seemingly 3D high-definition.
Touring the Moon…the rugged Southern Highlands of the lunar surface
are rich in craters. To the southeast the famous crater Theophilus is
65 miles across. The raised triple-peaked central area is striking to
observe in your SW 120ED. The crater has massive walls and the basin is
14,000 thousand feet deep. One of the southernmost craters, Clavius, is
a very large crater 145 miles across. It is located south of Tycho. In
this same area can be found craters Maginus and Longomotanus which are
also very worthy of exploration. To the north, the young crater Tycho
dominates the southern lunar landscape. Named after the famous Danish
astronomer Tycho Brahe, it is a spectacular sight with very high-rimmed
walls. Your SW120ED will provide an impressive view. North of Tycho
appearing brightly in a basin is the famous Rupes Rect (the Straight
Wall), an 800 foot mountain that is a “must see" for amateur
astronomers. Your SW 120ED will show it clearly and sharply the way you
want to see it. On the north end of Mare Nubium, almost on the lunar
N-S and E-W center line can be found 3 craters grouped together:
Arzachel a young impact crater 60 miles across and 13,000 feet deep
shows a terraced structure and a system of channel-like narrow
depressions in its basin called “rilles". Nearby are Alphonsus, a 70
mile wide crater, and Ptolemaus a prominent ancient crater 90 miles
across with a heavily worn dark interior. The Earth’s Moon offers a
treasure trove of fascinating detail to explore with your SW 120ED-APO
EQ5 PRO. We have only featured a relative few examples of what is
available. The views you will experience are so clear and sharp it
might just feel like a veritable space-walk.
Planets are spectacular…the inner solar-system presents the
colorful rusty-red planet Mars. Mars is a challenge for amateur
astronomers, but your SW 120ED will show some very interesting detail.
Olympus Mons a volcanic crater 375-miles across and 16-miles high is
just one of the quests your capable SW120ED can tackle. Nirgal Vallis
is a channel 600 miles long that responds well to the razor sharp
contrast provided by the SW 120ED. The Grand Canyon of Mars, Valles
Mariners, dwarfs that of our Earth’s Grand Canyon, but it still
requires superb optics to view even though it is 150 miles wide and 4
miles deep. When prominent, the gleaming white Mars’ polar cap is in
stark contrast to the redish-orange surface landscape of the rest of
the planet. The SW 120ED will show you this detail like you want to see
it. The gas giant Jupiter displays its swirling equatorial bands in
high-definition with festoons, and tonality within the bands. With
regular observation you will be able to follow storms and disturbances
cross the planet in the southern equatorial band. Saturn’s storied
surface phenomenon is simply stunning. View the rings and clearly see
Cassini’s Division and cloud belts across the equator.
Wonders of Deep-Space…beyond the solar-system hunt down double stars
like Epsilon Lyrae, the “double-double" in Lyra. A 120mm ED-APO
refractor will provide a crisp well defined image on par with up to a
7" reflector. Always a star-party favorite, the beautiful double
Alberio located in the tail of Cygnus is sensational. Alberio appears
like a gold sparkler and its companion looks like a blue-green
sparkler. It is a perfect object to view with your SW 120ED. Algol, an
eclipsing variable star, sometimes called the “winking eye" fluctuates
in brightness and is a suitable subject for the SW 120ED. Aldebaran, a
beautiful orange giant in Constellation Taurus is a delightful sight to
view with the SW 120ED. In the eastern corner of Constellation Orion,
Rigel, a bright blue double has a blue-green companion that requires
excellent optics to see, a worthy subject for the SW 120ED. Tight
globular star clusters like M13 in Constellation Hercules appear like a
beehive of crisp stellar pin points circling the central core, star
upon thousands of stars. Compact globular star clusters lend themselves
well to a refractor. M5 is a worthy object for viewing. M92 in
Constellation Hercules is very compact globular with a bright core. It
is a great object to view with the SW 120ED. M4, M10 and many other
globular clusters can be seen well with the SW 120ED-APO refractor. The
bright central cores of prominent nebulae can be seen and the brightest
stars can be observed illuminating the glowing nebulosity which appears
as ghostly apparitions.
The superb capabilities of the SW 120ED
provide performance on a par with a reflector of perhaps up to 7" in
diameter on lunar, planetary, double-stars, globular star clusters, and
depending on your ranking of unobstructed high-contrast as a necessary
attribute, even the brighter nebulae may look better to you in a SW
120ED. These objects will stand out in bold relief contrasted against a
very dark velvet-black sky background. Many advanced amateur
astronomers feel the ED-APO experience is astronomy’s richest.
As an astrograph, the SW PRO 120ED APO performs superbly delivering
crisp, high-fidelity imaging of planetary, lunar and aperture
appropriate deep-space phenomenon.
Refractors - the Ultimate Imaging Instruments
In a given aperture size, refractors will always exhibit sharper
images than other optical designs because the refractor concentrates
more light into the central airy-disk and first diffraction rings.
There is no diffraction pattern interference caused by a diagonal
mirror, or secondary mirror being suspended in the optical path
(central obstruction) as is the case with reflectors.
Sky-Watcher ED-APOs - the Ultimate Refractors
Sky-Watcher ED-APO refractors provide the finest images obtainable -
bar none - in their design class. If you are on a quest for the
ultimate in pristine, near textbook-perfect astronomical imaging, look
no further! Sky-Watcher ED apochromatic refractors deliver dramatic
coal-back skies and faithful, contrast-rich views of planetary and
deep-space phenomenon that are second to none. Sky-Watcher ED-APO
refractors are the logical choice as an investment in advanced
instrumentation for exceptional viewing or photography.
Virtually Eliminates Residual Chromatic Aberration
The Sky-Watcher ED-APO design assures virtual elimination of
secondary, residual “false color" normally present in 2-element
achromatic lens designs using Crown and Flint glass. Sky-Watcher APO
refractors utilize a second lens element made from the mineral fluorite
instead of Flint glass. Fluorite, CaF2, is a halide with unique
properties and a hardness of only four. It is an exotic and difficult
material to fabricate into a lens. Hence the cost of manufacturing a
fluorite lens is quite high compared to a Flint lens element, for
instance.
Why fluorite? Fluorite’s molecular properties have several distinct
advantages. First, it has superior dispersion characteristics compared
to pure silica-based glass. It functions as a high-index lens with very
low dispersion. We use the term ED to signify “Extra-low Dispersion".
Fluorite also corrects well for spherical aberration. Sky-Watcher
utilizes only the very finest available fluorite lens, FPL-53.
Schott Glass Used in Selected Models for Crown Element
Select models of ED-APO refractors will benefit from the inclusion of
Schott glass being used for the positive front Crown element in the
objective. Schott is the recognized world leader in glass utilized for
precision optical lens systems, including medical instrumentation, and
famous-brand camera lenses. While Schott glass is only used in selected
models, all other models utilize top-quality, Grade-A glass from
perhaps less famous but, nonetheless, highly respected, high-quality
glass manufacturers.
Pride and Perfection in Optical Manufacturing
Every lens element is individually inspected for purity and absence
of striae and other image-degrading imperfections. Every lens is
pitched polished to exacting standards of optical fabrication and
performance by highly skilled opticians utilizing state-of-the-art
methodology and rigidly controlled optical testing procedures. The
result is high-quality, diffraction-limited optics performing to the
theoretical limits of their respective aperture sizes. All lenses are
uniformly air-spaced in their cell housings.
Sky-Watcher offers one of the most extensive lines of
ED-APOCHROMATIC refractors in the world. Using only the finest
fabrication materials available, Sky-Watcher APO refractors are
manufactured to painstakingly rigorous, exacting standards of optical
and mechanical quality to insure the amateur astronomer peak
performance and a great experience each and every time a Sky-Watcher
ED-APO is taken into the field. We know the amateur astronomer has very
high expectations regarding astronomical equipment purchases.
Sky-Watcher has been delivering consistent satisfaction for over a
decade.
Metallic High-Transmission Lens Coatings
Each air-to-glass lens surface has exotic anti-reflection metallic
coatings applied to ensure optimum light through-put. The proprietary
Sky-Watcher “Metallic High-Transmission Coatings" (MHC) are the finest
photon anti-rejection coatings in their class.
Light-Baffled Optical Systems
The objective lens cell is light-baffled to reject stray, unfocused
light. The draw tube is likewise baffled to insure optimum contrast.
The tube interior is flat blackened to help prevent unfocused internal
light reflections from reaching the focal plane.
Precision 2" Crayford-style Focuser is Standard
Optical focus is achieved by means of a mechanically ultra-smooth, backlash-free, precision 2" Crayford-style rack & pinion focuser-assembly. This focuser offers 2-speed fine and ultra-fine focusing adjustments.
Tube Materials
The optical tube material is aluminum, powder-coated reflective
gloss black with gold fleck accent. The front and back cells are
cast-aluminum painted white, or black.
Telescope Tube Attachment Hardware:
The Sky-Watcher APO optical tubes come with attachment hardware that
allows them to be securely fastened to the SW EQ5P mount. The
quick-release tube rings provided with SW ED-APO models 80ED 100ED and
120ED are cast-aluminum, painted white.
Specifications:
