SKY-WATCHER EvoStar 120ED APO REFRACTOR: 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 embedded 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 EvoStar 120ED APO Refractor
The additional aperture compared to a 100 mm 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 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 Recta (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 its equator.
View Wonders of Deep-Space…beyond the solar-system hunt down double stars
like Epsilon Lyrae, and the “double-double” in Lyra. A 120 mm 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 the 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 the 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 the 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 EvoStar 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-black 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 residual
“false color” (i.e. chromatic aberration) normally present in 2-element
achromatic lens designs which utilize standard crown and flint glasses.
Sky-Watcher APO refractors utilize the finest extra-low dispersion
(ED) glass available, FPL-53. This results in the best color correction
for an ED doublet lens.
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 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 compatible mounts. The
quick-release tube rings provided with SW ED-APO models 80ED, 100ED and
120ED are cast-aluminum, painted white.
Included Components for Selected Models
All Sky-Watcher USA EvoStars come with 2-speed backlash-free 2”
Crayford-style focusers and quality foam-lined metal carrying cases as
standard equipment. EvoStars are also supplied with right-angle 8x50mm
viewfinder with bracket; 2” dielectric diagonal; two 1.25” LE (Long Eye
relief) eyepieces (LET20mm and LET5mm); 1.25” focuser adaptor; and tube
ring attachment hardware that works with compatible mounts.
Specifcations
| Refractor Design |
Apochromat
(APO) |
|---|
|
Number of
Refractor Elements
|
2 |
|
Telescope
Aperture |
4.7" |
|
Telescope
Focal Ratio |
f/7.5 |
|
Telescope
Focal Length (mm)
|
900 |
|
Optical
Coatings |
Metallic
High-Transmission Coatings
|
|
Limiting
Stellar Magnitude
|
12.9 |
|
Lowest
Useful Magnification
|
17x |
|
Highest
Useful Magnification
|
283x |
|
Light-Gathering Power Compared to Human Eye
|
294x |
|
Diagonal
Included? |
Yes - 2"
Star Diagonal |
|
Telescope
Eyepiece(s) Included?
|
Yes - 2
Eyepieces Included
|
|
Finder
Included? |
Yes - 8 x 50
Finder Included |
|
Includes
Telescope Case? |
Yes |
|
Focuser
Style |
Crayford/Crayford Style
|
|
Focuser Size |
2" |
|
Focuser
Speed |
Dual Speed |
|
Telescope
Mount Type |
No Mount -
OTA Only |
|
Telescope
OTA Width (in.) |
5.625 |
|
Telescope
OTA Length (in.) |
36 |
|
Telescope
OTA Weight with Accessories (lb.)
|
13.9 |
In the Box
- Sky-Watcher Evostar PRO 120 mm f/7.5 ED APO OTA
- 2" Dual-Speed Crayford-Type Focuser with 1.25" Adapter
- 8x50 RA Erect Image Finderscope
- 2" Dielectric Diagonal
- 20 mm 1.25" Eyepiece
- 5 mm 1.25" Eyepiece
- Tube Ring Attachment Hardware
- Foam-Lined Aluminum Carrying Case
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