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Celestron Advanced C11-SGT-XLT
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11" Schmidt-Cassegrain - StarBright XLT Optics - Fully Computerised
To order this item outside Great Britain, please contact us.
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- 11" Schmidt-Cassegrain Optical Tube
- 2800mm focal length (f/10)
- 40mm eyepiece included (70 x)
- Visual back allows for use with 1.25" accessories
- Star diagonal provides more comfortable viewing position
- Heavy Duty (CG-5GT) computerized German equatorial mount
- Ultra sturdy 2" diameter steel tripod with accessory tray
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Celestron Advanced C11-SGT-XLT
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Outline
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The largest aperture Advanced telescope in the series, this 11" Schmidt-Cassegrain
optical system is mounted on the computerized CG-5 EQ mount, which features
precision worm gears for extremely smooth motion. And with the heaviest
component under 30 lbs this telescope won't break your bank or your back.
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The C11 optical system comes with our premium StarBright® XLT coatings and
its large aperture offers light gathering power 1593 times that of the human
eye and 89% more than the 8" model. An optional polar alignment scope for
quick alignment is available.
Mounted on the Advanced GT Series computerized mount, this telescope has some high
performance software and hardware features. Operated by the proven NexStar® computer
control technology the telescope has a 40,000+ object database with 400 user-definable
objects and expanded information on over 200 objects.
Custom database lists of all
the most famous deep-sky objects by name and catalog number; the most beautiful double,
triple and quadruple stars; variable star; solar systems; objects and asterisms.
Using the RS-232 communication port on the hand control, you can control the telescope
via a personal computer and our new flash upgradeable hand controls allow you to update
your telescope's operating software via the internet. An autoguider port is also included
for astrophotography.
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Standard Features:
- 11" Schmidt-Cassegrain telescope
- StarBright XLT high transmission coatings
- 9x50 finderscope to help accurately find objects
- Heavy Duty (CG-5GT) computerized German equatorial mount
- Ultra sturdy 2" diameter steel tripod with accessory tray
- Star diagonal provides more comfortable viewing position when observing objects that are high in the sky
- Includes CD-ROM "The Sky" Astronomy Software which provides education about the sky and printable sky maps
- Proven NexStar computer control technology
- 40,000 object database with 400 user-definable objects and expanded information on over 200 objects
- Custom database lists of all the most famous deep-sky objects by name and catalog number; the most beautiful double, triple and quadruple stars; variable star; solar systems; objects and asterisms
- DC Servo motors with encoders on both axes
- Flash upgradeable hand control software and motor control units for downloading product updates over the Internet
- Autoguider port for long exposure astrophotography
- Double line, 16-character Liquid Crystal Display Hand Control with backlit LED buttons for easy operation of goto features
- Compatible with optional NexRemote telescope control software, for advanced control of your telescope via computer
- RS-232 communication port on hand control to control the telescope via a personal computer
- GPS-compatible with optional CN16 GPS Accessory (93966)
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CG-5 Mount - precision engineered for stability
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This new German Equatorial mount has precision worm gears on both axes for
extremely smooth stability. The key element that makes this system the most
stable in its class is the new heavy-duty tripod with larger and more substantial
legs that offer excellent damping characteristics for more stable views.
The CG-5 also has a convenient latitude scale for easier alignment and an
optional polar finder scope for the ultimate in precision.
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S.C.T. Optical Design
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There has been much said and written regarding the optics in the SCT. Essentially,
the combination of a spherical primary, an aspherized secondary and a Schmidt plate
(a thin glass plate, plano (flat) on one side, and with the Schmidt curves on the other),
creates a wavefront that is free from Lower Order Spherical aberration (LSA), free
from Higher Order Spherical aberration (HSA or zones), a diffraction limited field
free of coma and astigmatism, and the field free of Chromatic aberration (CA).
- The design has much greater freedom from off-axis coma than the equivalent focal ratio Dall-Kirkham.
- Much greater freedom from off-axis coma than the focal ratios usually found in Newtonians.
- Does not suffer from the tube currents common in open tube Cassegrain focus designs, such as the Dall-Kirkham, the Klevsov, the sub-aperture meniscus Maksutov and the standard Cassegrain, nor does it require regular cleaning of the primary optics because the closed tube keeps dust and debris out.
- It has a smaller secondary than the photographic Ritchey-Chrétien.
- It has none of the chromatic aberration associated with achromatic refractors.
There are other ways to design a catadioptric system at f/10 using the full aperture Schmidt
type correcting plate, by generating a different aspheric curve on the secondary. However,
for production purposes, the difficulty lies in producing a diffraction limited instrument
using a different aspheric curve on the secondary, on a consistent basis. Regardless of
theoretical advances that other designs may promise, the key lies in the consistent diffraction
limited performance that is actually realised when a catadioptric telescope is factory produced.
Celestron’s original tried and tested method has worked and worked very well over the decades,
one of the reasons the C6 has become an instant classic. Many competing catadioptric telescopes
have found it difficult to match the optical consistency of Celestron.
The Celestron Schmidt Cassegrain design is also beneficial for planetary imagers over other
catadioptric designs such as the Maksutov Cassegrain (both the standard Gregory type and the
separate secondary configuration), due to the cooling times of the thick meniscus lens on Maksutovs.
Maksutovs often show correction errors for long periods of time whilst cooling. On the larger
instruments (greater than about 180mm) this can be quite protracted. The problem is often due
to the differential cooling periods of both the primary mirror and the meniscus. For planetary
imagers, this can sometimes mean an unproductive night waiting for spherical aberration to reach
a minimum. The Celestron Schmidt Cassegrains cool at a much faster rate, which means a much longer
period of observation with the telescope at optimum correction.
Celestron’s Schmidt Cassegrains offer the amateur astronomer or the optical enthusiast the complete
“owning a telescope” experience. The apertures range from five inches to fourteen inches and focal
lengths between 1250mm and 4000mm. They are a very good choice for planetary imagers, and deep-sky
imagers because of the range of image scales. They represent the ideal observing instrument with
medium to large apertures, medium to longer focal lengths for the comfortable use of higher
magnifications, a large diffraction limited field free of aberrations, and rear eyepiece positioning
for relaxed long periods of observing. The closed tube design keeps the important optical surfaces
clean and prevents image-destroying tube currents seen in some Newtonians. The primary mirror focusing
system permits close focusing with minimum spherical aberration, whilst enabling the observer to vary
image scale, and all of this potential and performance in a closed compact easy to handle optical
tube assembly.
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| Technical Specification |
| OPTICAL DESIGN |
Schmidt-Cassegrain |
| APERTURE |
280 mm (11.02 in) |
| FOCAL LENGTH |
2800 mm (110.24 in) |
| FOCAL RATIO |
10 |
| EYEPIECE 1 |
40 mm (1.57 in) |
| MAGNIFICATION 1 |
70 x |
| FINDERSCOPE |
6 x 30mm |
| STAR DIAGONAL |
1.25" |
| MOUNT |
CG-5 Equatorial |
| TRIPOD |
2 inch Stainless Steel |
| OPTICAL TUBE |
Aluminium |
| FASTAR COMPATIBLE |
Yes |
| ACCESSORY TRAY |
Yes |
| CD ROM |
The Sky Level 1 |
| HIGHEST USEFUL MAGNIFICATION |
660 x |
| LOWEST USEFUL MAGNIFICATION |
40 x |
| LIMITING STELLAR MAGNITUDE |
14.7 |
| RESOLUTION |
0.5 arc seconds |
| RESOLVING POWER |
0.42 arc seconds |
| PHOTOGRAPHIC RESOLUTION |
200 line/mm |
| LIGHT GATHERING POWER |
1593 x |
| ANGULAR FIELD OF VIEW |
0.71 ° |
| LINEAR FIELD OF VIEW (@1000 YDS) |
38 ft (11.58 m) |
| SECONDARY MIRROR OBSTRUCTION |
3.75 in (95.25 mm) |
| SECONDARY MIRROR OBSTRUCTION BY DIAMETER |
34.1 % |
| SECONDARY MIRROR OBSTRUCTION BY AREA |
12 % |
| OPTICAL COATINGS |
Starbright XLT |
| OPTICAL TUBE LENGTH |
24 in (609.6 mm) |
| TELESCOPE WEIGHT |
91 lb (41.28 kg) |
| COUNTERWEIGHTS |
3-11lb |
| AC ADAPTER |
Car Battery Adapter |
| MOTOR DRIVE |
DC Servo motors with encoders, both axes |
| SLEW SPEEDS |
3°/sec |
| COMPUTER HAND CONTROL |
Double line, 16 character Liquid Crystal Display; 19 fiber optic backlit LED buttons |
| TRACKING RATES |
Sidereal, Solar and Lunar |
| TRACKING MODES |
EQ North & EQ South |
| ALIGNMENT PROCEDURES |
AutoAlign, 2-Star Alignment, Quick Align |
| SOFTWARE PRECISION |
24bit, 0.08 arcsec calculation |
| COMMUNICATION PORTS |
RS-232 communication port on hand control |
| MOTOR PORTS |
Aux Port, Autoguide Ports |
| DATABASE |
40,000+ objects, 400 user defined programmable objects. Enhanced information on over 200 objects |
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Notice
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We are constantly checking the accuracy of the technical data. We are prepared
to provide more detailed information on request. Technical data is subject to
change without notice.
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Promotional Offer
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Cash Back on Opticstar
Imaging Products
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updated: 4th August 2010
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Customers who purchase any Celestron telescopes or Celestron optical tubes
or Celestron mounts
listed on this page qualify for a 10% cash back on any Opticstar astronomy
cameras purchased at the same time or at a later date.
This offer is valid for 1 year commencing on the date that the Celestron
product is purchased from the Opticstar website or the Opticstar showroom.
Any additional purchases at a later date of Celestron products that qualify for
this offer will renew the cash back period to 1 full year.
Opticstar astronomy cameras that qualify for this offer include the following:
Once an Opticstar CCD or CMOS camera has been purchased within a year of
the qualifying Celestron purchase, the cash back can be claimed by contacting
Opticstar by email or over the phone quoting the receipt number(s). Please
allow up to 14 days to process the payment.
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Sample Images
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Opticstar DS-145M ICE
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posted: 13th March 2009
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The M20 nebula shot by John Haunton with the Opticstar DS-145M ICE.
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Sample Images
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Opticstar PL-130M CoolAir
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posted: 10th February 2009
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An impressive 9.4 megapixel mosaic of the Moon by Herwig Sulzbacher with
the Opticstar PL-130M.
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Feedback
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We want to hear your comments.
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Sample Images
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Opticstar DS-335C ICE
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updated: 20th August 2010
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The M8 nebula shot by John Haunton with the Opticstar DS-335C ICE.
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Product Reviews
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Apogee Alta
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updated: 14th February 2009
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"The quality exceeds anything I've been able to do in the past
with film or any other CCD camera."
Senior Editor Dennis di Cicco of Sky & Telescope
in a Test Report, June 2007 issue.
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Manufacturer Spotlight
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Orion Optics
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updated: 4th August 2010
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The new AG Advanced Astrographs from the ever expanding range of telescopes from
Orion Optics combine their high quality standards with new advanced optical designs...
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A&M 80mm f/6 Review
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"Best Of Breed"
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updated: 25th March 2009
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The A&M 80mm f/6 A&M/TMB has been
reviewed in Cloudy Nights
and it has been hailed as the "best of breed". The review concludes by saying "offers
stunning performance while standing out from the crowd, look no further".
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Willmann Bell
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Books for Astronomy
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posted: 29th August 2008
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Acclaimed books from Willmann Bell...
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