Celestron - CGX-L Equatorial 1100 11" Schmidt Cassegrain Telescope - 12071
- Cutting edge optics with the Celestron 11" SCT design, an astrophotographer must have!
- Celestron Starbright XLT Coatings renders excellent quality views and images
- The Fastar application turns an f/10 system to an f/2 for very short exposure times
- Lightweight and portable enough for relatively easy transportation
- The CGX-L has built-in physical hard stops and optical hard stops eliminating the chance that the counterweight shaft will strike the leg.
- Designed for easy remote control, home sensors allow you to start in the index position no matter what position the mount was in when it was powered off.
- Includes a USB 2.0 Nexstar+ hand controller equipped with Celestron's PWI telescope control software designed in partnership with PlaneWave Instruments, featuring multi-point mount modeling for precision pointing accuracy.
- Includes Celestron's All Star Polar Alignment for incredibly accurate guided polar alignment allowing you to align with any bright fixed object in the night sky. There's no need for additional polar finders or accessories.
- The head of the Celestron CGX-L is fully adjustable allowing you to slide the telescope perfectly over the center of gravity and take full advantage of the 3º-65º latitude range.
Celestron - CGX-L Equatorial 1100 11" Schmidt Cassegrain Telescope - 12071
Celestron - C11-A XLT - 11" SCT OTA for CGE/CGX - 91036-XLT
The Celestron C11 11" SCT Optical Tube Assembly is an excellent gem for serious astrophotgraphers who enjoy crisp images with shorter exposure times. Being lightweight with its aluminum design, it is only 24" in length with a weight of 27.5 pounds, thus still making is reasonably portable to be taken to locations for viewing or imaging with one person.
Using the Celestron Starbright XLT Coatings, high contrast views at high magnification are a walk in the park! The coatings increase contrast and light transmission; significantly improving image quality to very superior standards which is a major plus for shorter exposure astrophotography. When taking into account the durability of the Fastar system as well as the f/6.3 focal reducer, making shorter exposure times even better at 25 times shorter at f/2 than its typical f/10 optical focal ratio.
Features
- Cutting edge optics with the 11" SCT design, an astrophotographer must have!
- Starbright XLT Coatings renders excellent quality views and images
- The Fastar application turns an f/10 system to an f/2 for very short exposure times
- Lightweight and portable enough for relatively easy transportation
Starbright XLT Coatings
- Maximizing light transmission through a perfect optical path
- Starbright XLT improves color retention, contrast, sharpness, resolution, and brightness
- Starbright XLT system provides flat wavelength transmission across the entire visual spectrum. Therefore you will minimize your wavelength curvature
- Multi-layer mirror coatings with layers of aluminum, TiO2 (titanium dioxide) and SiO2 (quartz),
- Starbright XLT Multi-layer anti-reflective corrector plate coatings with layers of MgF2 (magnesium fluoride) and HfO2 (hafnium dioxide); hafnium has a wider band-pass than the commonly used titanium in lesser quality optics
- Starbright Xtra High-Transmission water white glass corrector plate limits loss of light due to absorption
Optical Coatings
Since Schmidt-Cassegrain designs use both mirrors and lenses, obtaining maximum light transmission without sacrificing quality is the key. This is where the StarBright XLT coatings come into play.
Using a technique known as "vacuum deposition", optical coatings are applied in a thin manner on the optical glass components and positioned properly relative to each other to maximize light transmission. The mirror is coated with metallic coatings that effectively increases light transmission from 4% for mirrors without coatings and 86-88% with standard coatings to a whopping 95%. This is the first step to achieving the necessary light transmission.
The second step is applying the coatings to the lens which is more sophisticated and complex process due to the fact that light is lost in both the reflection and absorption, thus resulting in further light loss. 4% is reflected back intially while more light is lost in the absorption through the glass and second lens surface. To solve this problem, Celestron has implemented dielectric materials known as A/R (anti-reflection) coatings to obtain a very low and flat reflection across the visible spectrum.
Combining these factors results in a remarkable peak transmission of 89% at 520nm and an overall average transmission of 83.5% from 400 to 750nm. The graph below demonstrates this.
How Starbright XLT is Different
The charts below show the improvement of transmission, reflectivity and corrector transmission obtained through Starbright XLT coatings verses previous coatings. It has a peak transmission of 89% vs the previous Starbright peak of 80%. In terms of reflectivity, the XLT coatings have an average peak of 93% vs previous coatings at 91%.
The Starbright XLT corrector transmission is 97.4% compared to other coatings with a lower peak.
Coating Testing
Celestron has implemented two methods to test the effectiveness of the StarBright XLT coatings.
The first method is by measuring the optical tube performanec in its entirety. This is done by comparing a beam of light passing through the optical components of the optical tube against a beam of light in air. By dividing the light ratio of the beam through the optical tube verses the beam through air, Celestron can measure the effectiveness and performance. However there are challenges to this method including but not limited to making sure the beam is constant and that light capture is effective, steady and clean and making sure the optical components are properly lined up so they don't skew the results in one way or another.
The second method is easier to execute and simply measures each component's spectrographic performance to make sure all are working properly. This method in addition to not having the setbacks of the first method, also provide greater analysis of each individual component of the optical tube, something not possible in the first method. This method also helps determine the upper limit of the telescope's upper throughput using the calculation below:
%TT = %TC x %RP x %RS
%TT is Total Telescope Throughput
%TC is Corrector Plate Transmission
%RP is Primary Mirror Reflectance
%RS is Secondary Mirror Reflectance
Corrector Plate Transmission - %TC
Using a Shimadzu UV1601 spectrophotometer, Celestron has implemented an effective way of analyzing the corrector plate transmission by using a double beam instrument with a 190 to 1100 nm spectral range with transmission usually collected within 400 to 750 nm. To avoid scratching and damaging the correct plate in the process, "witness plates" which are small samples of the corrector material are used as an alternative. This method is effective for correctors up to 8" diameter.
Primary and Secondary Reflectance - %RP, %RS
The protocol to measuring the reflectance of the primary and secondary mirrors also includes the use of "witness plates". Using 1-2" diameter polished glass substrates coated along with the primary and secondary mirrors that serve as a "stand in" for the mirrors during the testing to avoid unnecessary scratching and damage and to serve as an easy reference to measure reflectance on flat surfaces.
Celestron chose to use enhanced aluminum-coated quartz flat scaled and measured against a NIST (National Institute of Standards and Technology) specular reflectance standard. The formula to measure the reflectance is calculated by comparing it against the baseline formula below:
%RS = %RSR x %RR
%RS is Sample Reflectance Factor
%RSR is Reference Standard
%RR is Reference Standard Known Reflectance
Flat mirrors are very easy to measure using the formula above, but curved primary and or secondary mirrors on the other hand, that is a totally different story, particularly if there are no witness plates available for use. Measuring a curved mirror against a flat reflectance standard would not render accurate results. As an alternative, another method is used known as an integrating sphere. This method essentially ignores the curvature and simply measures light intensity. The downside however is this is a pricey and long process to setup. To bypass this time and cost restraint, Celestron has developed another method by creating their own reference standard for secondary and primary mirrors. By using secondary and primary mirrors that have existing coating removed and replacing it with flat witness plates scaled against the NIST standard, the data can then be applied to the curved samples. The instrument used in this process are an Ocean Optics USB2000 Spectrometer with an LS-1 Tungsten Halogen Light Source. This single beam instrument has a 0.3nm resolution with a 340-1024 nm scanning range and is equipped with a fiber optic curved surface reflectance measuring probe.
Celestron CGX-L Mount
Part of the next generation of equatorial mounts from Celestron, the CGX-L features a robust load capacity of 75 pounds with an excellent load to weight ratio. Designed with imaging in mind, you will find additional auxiliary ports and an autoguiding port on the dec for improved cable management. Worm gears have been upgraded to a larger (compared to previous models) 144mm gear for excellent tracking and slewing with heavy loads and smart design improvements like a longer saddle plate and 2.75" provide a highly stable and secure platform for your large aperture telescope.
With a shorter, more compact mount head and built in handles, the CGX-L is surprisingly easy to carry and assemble. As part of it's ergonomic design, the adjustment knobs are designed for reduced friction and a stationary latitude knob with a newly-designed linkage system greatly reduces the amount of friction when polar aligning the mount. Teflon bearings on the azimuth adjustment allow you to adjust even with a full load on the mount and an the latitude scale is large, clear and easy to read
CGX-L Features:
- 75 pound load capacity
- A shortened mount profile creates a more compact mount that is easier to carry and assemble but also improves the mounts central gravity boosting load capacity.
- High torque motors with better slewing and tracking ability.
- A belt driven motor minimizes backlash but remains smooth even when handling a large telescope. A clear window allows you to easily monitor the motor.
- Spring loaded brass worm wheel and stainless steel worm gear. By spring loading the motor worm and gear, gear friction is greatly reduced and optimal gear mesh is maintained.
- Internal cabling keeps your mount free from cable clutter and reduces the chance of snagging wiring. The power input port and accessory ports stay in one position at all times.
- The CGX-L has built-in physical hard stops and optical hard stops eliminating the chance that the counterweight shaft will strike the leg.
- Designed for easy remote control, home sensors allow you to start in the index position no matter what position the mount was in when it was powered off.
- Includes a USB 2.0 Nexstar+ hand controller equipped with Celestron's PWI telescope control software designed in partnership with PlaneWave Instruments, featuring multi-point mount modeling for precision pointing accuracy.
- Includes Celestron's All Star Polar Alignment for incredibly accurate guided polar alignment allowing you to align with any bright fixed object in the night sky. There's no need for additional polar finders or accessories.
- The head of the Celestron CGX-L is fully adjustable allowing you to slide the telescope perfectly over the center of gravity and take full advantage of the 3º-65º latitude range.
- Includes a dual saddle plate to accommodate both D and V series dovetail plates.
- +20º of additional tracking past the meridian on either side
- The 2.75" steel tripod has been newly designed for the CGX-L with a wider stance and a lower minimum height than it's predecessors.
- 2 autoguider ports for better cable management.
- PEC sensor and PPEC ready.
- A threaded power connector to ensure your mount never comes disconnected at the base.
- A red lit on/ off switch makes it easy to find in the dark.
- Internal Real Time Clock.
Celestron - 22 lb. Counterweight for CGE Pro, CGEM DX, CGE or CGX-L
Plan on viewing or imaging with an equatorial mount, you'll need to balance and compensate for the weight of the OTA and accessories. Counterweights are not an option! Failure to do so could cause OTA damage, and issues with the mount motors and tracking. Luckily, the Celestron 22 lb counterweight is exactly what you'll need! It works with the CGX-L, CGE Pro and CGEM DX Mounts!
Features:
- Fits with 32mm counterweight shafts
- Sturdy lock knobs
UPC | 050234120715 |
---|---|
Brand | Celestron |
Free Shipping | Free Shipping Available |
Aperture | 279.4mm (11") |
Case Included | No |
Focal Length | 2800mm (110") |
Focal Ratio | f/10 |
Focal Length of Eyepiece 1 | 40mm (1.57") |
Magnification of Eyepiece 1 | 70x |
Finderscope Included | 9x50 |
Diagonal Included | 1.25" Star Diagonal |
Optical Tube Material | Aluminum |
Highest Useful Magnification | 660x |
Lowest Useful Magnification | 40x |
Limiting Stellar Magnitude | 14.7 |
Resolution - Rayleigh | 0.5 arc seconds |
Resolution - Dawes | 0.42 arc seconds |
LIght Gathering Power (Compared to the Human Eye) | 1593x |
Size of Secondary Obstruction | 95mm (3.75") |
Secondary Mirror Obstruction By Diameter | 34% |
Secondary Mirror Obstruction By Area | 12% |
Optical Coatings | Starbright XLT |
Optical Tube Length | 610mm (24") |
Optical Tube Diameter | 312.42mm (12.3") |
Optical Tube Weight | 27.5 lbs (12.4 kg) |
Included Dovetail | CGE Dovetail Bar |
Mount Load Capacity | 75 lbs (34 kg) |
Accessory Tray Included? | Yes |
Counterweights Included | 2 x 22 lbs |
Tripod Height Adjustment Range | 908.05mm - 1339.85mm (35.75" - 52.75") |
Adjustable Legs? | Yes |
Tripod Leg Diameter | 69.85mm (2.75") Steel tripod with graduated markings on lower section |
Tripod Weight | 46.2 lbs (21 kg) |
Mount Head Weight | 52.6 lbs (23.8 kg) |
Slew Speeds | 9 slew speeds - max speed 3°/second |
Tracking Rates | Sidereal, Solar and Lunar |
Tracking Modes | EQ North & EQ South |
Mount Motor Drive | DC Servo Motors |
GPS | No |
Number of Auxiliary Ports | 4 Aux ports (Hand Control can use any Aux port, 2 are located near dovetail saddle) |
Includes Autoguide Port | Yes |
USB Port | Yes, input for Mount and Hand Control |
Power Requirements | 12V DC, 3 amps |
Computerized Hand Controller | Double line, 16 character Liquid Crystal Display; 19 fiber optic backlit LED buttons, USB 2.0 port for PC connection |
Alignment Procedures | 2-Star Align, 1-Star Align, Solar System Align, Last Alignment, Quick Align |
Database | 40,000+ objects, 100 user defined programmable objects. Enhanced information on over 200 objects |
Included Software | CPWI Telescope Control Software, Celestron Starry Night Special Edition Software, SkyPortal App |
Periodic Error Correction | Yes |
Total System Weight | 170.3 lbs (77.11 kg) |
Warranty | 2 Years |
In The Box |
|
- Celestron 11" SCT Optical Tube Assembly
- CGX-L Equatorial Head
- CGX-L Tripod
Accessory Tray - 2 x 22 lbs counterweights
- NexStar+ Hand Control
- DC Power Cable (item# 18769)
- 8mm Allen wrench (contained in rear carry handle)