Feature
highlights:
- 2-element precision optics made
from special low-dispersion glass
- Short focus, compact design for
wide-field viewing or high-powered imaging
- Integrated dovetail mounting
plate for Vixen-style mount or ¼”-20 camera tripod
- Dual-speed focuser with 5kg
carrying capacity
- Carbon fiber tube
Short tube
refractors have become a staple of amateur astronomy, and Canadian Telescopes’
80ED apochromatic refractor stands out from the crowd. The versatile 80ED offers pinpoint
stars and outstanding color in a compact package for visual observers, expert
imagers and astronomers on the go.
The 80ED’s
apochromatic lens is made from super-low dispersion FPL-53 ED
glass for sharply-defined images free of the false color found in lesser achromatic
refractors. Its compact design,
carbon fiber tube, light weight and included hard case with die-cut custom foam
make it a great grab-and-go scope as well. The 80ED’s built-in mounting plate attaches to any
Vixen-style mount, or to a camera or other general-purpose tripod with standard
¼”-20 thread. Whether mounted atop
a sturdy camera tripod for visual observing, or atop a precision mount for astrophotography,
the 80ED is a true all-around telescope.
The 80ED’s
short focal length (500mm, f/6.25) provides sweeping wide-angle views of the Milky
Way, while its precision optics let you move in for finely-detailed
high-magnification views and imaging of planets. The rugged, high-precision 2-inch Crayford focuser can
handle an impressive 5 kg of attached equipment. Separate knobs allow for fast and fine focusing, and an
adaptor is included for 1.25-inch eyepieces. The (optional) red dot finder makes locating your target a
snap, and an integrated dew shield extends to keep the lens dry and block stray
light from your surroundings.
Whether
you’re heading out for a quick look at Jupiter’s Red Spot, heading to a
dark-sky site, or planning an all-night astrophotography session, Canadian
Telescopes’ 80ED apochromatic refractor is the perfect companion to take along.
Specifications:
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Telescopes can have multiple uses depending on their design.
Refractors and Cassegrains can provide a "correct-image" view, so
they can be used for daytime land viewing as well as astronomy. Reflectors
render the image upside down so they are not recommended for daytime viewing.
This is not an issue for astronomy, however, because there's no
"right-side up" in space.
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Beginner - Telescopes suited
for beginners are easy to use and maintain. Very good optical and mechanical
quality. A great first telescope that will show you the moon and planets.
Intermediate -Telescopes for the
intermediate user are more robust in features and performance. Excellent
quality in optics and mechanics, and more complex in use. An intermediate
telescope will allow an enthusiast to "grow" in the hobby.
Advanced - Advanced
telescopes are high performance, with exceptional quality. They may require
more commitment to use in set-up time and technical savvy. Some advanced telescopes
are easy-to-use but large and heavy. An advanced telescope is a purchase for a
lifetime.
Expert - Expert telescopes
offer uncompromising optical and mechanical quality for the most demanding
amateur astronomer. They may be technically involved or designed for
specialized use, such as astrophotography or detailed deep sky observation.
They carry a premium price; but are designed to provide the ultimate
performance in the field.
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A small, quality achromatic refractor of 60mm to 80mm aperture
makes a fine starter scope for observing the Moon and major planets. They're
affordable ($100 to $350), portable, and maintenance-free, all desirable
factors if you're just "testing the waters" of Astronomy. If nebulas
and galaxies are your main interest, a Newtonian reflector or
Schmidt-Cassegrain is the way to go. Moving up to a 90mm or 100mm refractor
will snare more objects and provide better performance, for a higher price.
Renowned for crisp, sharp images, refractors are the priciest per inch of
aperture of all telescope types. A refractor is the scope of choice if you will
be doing most of your stargazing from city or suburbs, where the night skies
are moderately light-polluted. Since viewing is restricted mostly to the Moon
and planets a big scope would only amplify the skyglow, yielding poor washed
out images. Reflectors Newtonian reflectors are great all-around scopes,
offering generous apertures at affordable prices. They excel for both planetary
and deep-sky viewing. Of course, the larger the aperture, the more you'll see.
Smaller, 3" and 4.5" equatorially mounted Newtonians will provide a
nice "survey" of celestial luminaries, and they maintain their
portability. Six-inch and 8" Newts have enough aperture to deliver
captivating images of fainter star-clusters, galaxies, and nebulas-especially
in a reasonably dark sky. Although the 6" to 8" Newts are bulkier and
weigh more, with a Dobsonian mount they are easily manageable by one person
making them a wonderful beginner scopes. Dobsonian-mounted reflectors have
lower price tags than their equatorial counterparts, starting in the mid-$300s
for a 6" Dob. Schmidt-Cassegrains If portability is important to you, you
might want to consider a "catadioptric" scope such as a Schmidt-Cassegrain
or Maksutov-Cassegrain. They pack a hefty aperture into a very compact tube. An
8" Schmidt-Cassegrain provides excellent views of the Moon, planets, and
deep-sky objects, and is well suited for astrophotography. Schmidt-Cassegrains
should be considered as an investment priced over $1000 for the most basic
8" models (and hundreds more to outfit it for astrophotography). The
Bottom Line Now that you've received the crash course on telescopes, here's
some parting advice for aspiring astronomers: Get as much aperture as you can
reasonably handle. Big aperture is desirable, however you don't want to end up
with a scope that is too big or complicated to conveniently set up, haul
around-and use! Also, avoid those gee-whiz, techno-toy scopes with the hefty
price tags that are showing up in the big chain stores. For a first telescope,
we recommend a basic refractor of 90mm aperture or smaller, or a Newtonian
reflector of 6" aperture or less, unless you're really committed. After
you've learned the basics of observing and developed an appreciation for the
hobby, then you can move up to a bigger, fancier scope.
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The optical diameter (also known as aperture), is the size of the
telescope's main light collecting lens or mirror, measured in millimeters or
inches. As the diameter increases, more light is collected and the resolution
increases.
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The distance from the center of a curved mirror or lens at which
parallel light rays converge to a single point. The focal length is an inherent
specification of a mirror or lens and is one of the factors in determining
resultant magnification for a telescope (along with the focal length of the
eyepiece being used).
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The focal ratio of an optical system is the ratio of a
telescope's focal length to its aperture. Short focal ratios (f/5, f/4.5)
produce wide fields of view and small image scales, while long focal lengths
produce narrower fields of views and larger image scales.
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Lenses are coated with an anti-reflective material to ensure that
as little light as possible is reflected away, thus more gets to your eye. Good
lenses are at least "fully coated," with a single layer of magnesium
fluoride applied to each air-to-glass lens surface. Multiple layers of coatings
are even more effective; the term "multi-coated" means one or more
lens surfaces have multiple coatings. "Fully multi-coated" is superior
because all lens surfaces are multiple-layer coated. Mirror star diagonals are
coated with a reflective material similar to telescope mirrors in order to
reflect the light into the eyepiece. Standard aluminum coatings reflect between
88%-92%, and enhanced aluminum reflects 97%. Dielectric coatings use a
different process to deposit a coating that reflects 99% of the light. In
addition to the higher reflectivity, Dielectric coatings are much more durable
than aluminum coatings, so they last longer and can be cleaned with less risk
of damage.
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Newtonian reflectors will have either a spherical shaped mirror,
which is less expensive to produce, or a higher quality parabola, which does
not result in spherical aberration. Cassegrain telescopes routinely use spheres
in addition to other lenses in the optical path to correct for residual
spherical aberration. Refractors use a series of lenses to provide a clear
image. Designs range from a standard air-spaced doublet (two lenses in a row)
to exotic designs such as oil-spaced triplets and 4-element multi group lenses.
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Refractors use glass lenses to focus the light, and the glass
material plays an important role in the quality of the resulting image.
Standard achromatic refractors routinely use Crown and Flint for the two
elements, but more expensive apochromatic refractors can use ED (extra low
dispersion) glass for one or more of the lenses. Reflector mirrors are made
from glass with different levels of thermal expansion. Standard mirrors are
made from material such as Soda-Lime Plate glass and BK-7 glass. Glass with
Pyrex or other low thermal expansion material will not change shape as
dramatically during the cool-down period, resulting in more stable images
during this period.
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The theoretical resolving power of a telescope can be calculated
with the following formula: Resolving power (in arc seconds) = 4.56 divided by
aperture of telescope (in inches). In metric units, this is: Resolving power
(in arc seconds) = 116 divided by aperture of telescope (in millimeters). Note
that the formula is independent of the telescope type or model, and is based
only upon the aperture of the telescope. So the larger the telescope's
aperture, the more it is capable of resolving. This is important to keep in
mind when observing astronomical objects which require high resolution for best
viewing, such as planets and double stars. However, it is usually atmospheric
seeing conditions (not the telescope) which limits the actual resolving power
on a given night; rarely is resolution less than one arc-second possible from
even the best viewing locations on Earth.
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Lowest useful magnification is the power at which the exit pupil
of the telescope (the beam of light exiting the eyepiece) becomes 7mm in
diameter. Powers below this can still be reached with the telescope to give
wider fields of view, but the image no longer becomes brighter at a lower
power. This is due to the fact that the exit pupil is now larger than the
average person's dark adapted pupil, therefore the eye cannot absorb any more
light.
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The highest practical limit is different from the often used
"highest theoretical magnification" specification. The
"theoretical" limit generally is 50x the aperture of the scope in
inches (2x the aperture in mm). So for example, an 80mm refractor is capable of
160x, and a 10" telescope is theoretically capable of 500x magnification.
But after approximately 300x, theory breaks down and real world problems take
over. The atmosphere above us is constantly in motion, and it will distort the
image seen through the telescope. This effect may not be noticeable at lower
powers, but at higher powers the atmosphere will dramatically blur the object,
reducing the quality of the image. On a good night (a night where the air above
is steady and the stars aren't twinkling), the practical upper limit of a large
telescope is 300x, even though the theoretical limit may be much higher. This
doesn't mean the scope will never be able to reach those higher
"theoretical" powers - there will be that rare night where the
atmosphere is perfectly still and the scope can be pushed past it's practical
limit, but those nights will be few and far between.
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The limiting stellar magnitude is a measure of the faintest star
you can see through the telescope.
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"Diffraction Limited" means that the limits of image
detail are determined by the physical properties of light, and not by optical
defects in the telescope.
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The astro-photographic capability of the telescope is based on
the style, stability, and accuracy of the mount and tripod. Telescopes on
either very lightweight mounts or non tracking mounts (such as Dobsonians) are
capable of only very short exposures such as lunar photographs. If a motor
drive is attached to an equatorial mount, even a small lightweight mount is
capable of capturing some planetary detail. Larger EQ mounts that utilize very
precise tracking and excellent stability are capable of longer exposure
deep-sky photography.
|
Objective
Lens Diameter
|
80mm
|
|
Focal
length
|
500mm
|
|
Focal
ratio
|
f/6.25
|
|
Coatings
|
Fully multi-coated
|
|
Glass
material
|
Extra
low-dispersion FPL-53
|
|
Resolving
power
|
1.45
arc-second
|
|
Lowest
useful magnification
|
12x
|
|
Highest
useful magnification
|
160x
|
|
Limiting
stellar magnitude
|
12.2
|
|
Optical
quality
|
Diffraction
limited
|
|
Finder
scope
|
N/A
|
|
Focuser
|
3-in.
dual-speed Crayford with 5 kilogram load capacity
|
|
Diagonal
|
N/A |
|
Astro-imaging
capability
|
Lunar,
planetary and deep sky
|
|
Tube
|
Carbon fiber
|
|
Length
of optical tube
|
14.3
in.
|
|
Weight,
optical tube
|
8.0
lbs.
|
|
Carry case
|
Custom
aluminum case with die-cut foam
|
|
Warranty
|
Two year
|