Celestron C11 XLT Advanced OTA
This OTA has been replaced with https://www.grovers.biz/optical-tube-assemblies/92-celestron-c11-xlt-cge-ota-050234103695.html
Warranty: 2 years
Celestron Schmidt-Cassegrain Optical Tube Assemblies (OTA) are available individually for use with your favorite mount. Each OTA is made to the same exacting standards as those used on all our high quality telescopes. All optical surfaces are coated with Celestron’s high efficiency StarBright® multi-layered coating group. These tube assemblies are equipped with the same dovetail mounting bar used on the CGE and Advanced Series for easy attachment to a variety of popular mounts.
• 11" Schmidt-Cassegrain Optical Tube Assembly
• Aluminum Optical Tube
• Celestron's premium StarBright XLT coatings
• 2800 mm focal length (f/10)
• 40 mm eyepiece included (70x)
• Visual back allows for use with 1.25" accessories
• 9x50 finderscope to help accurately find objects
• Star diagonal provides more comfortable viewing position when observing objects that are high in the sky
• Includes dovetail rail compatible with CG-5 Advanced Series mount
OPTICAL DESIGN : Schmidt-Cassegrain
DOVETAIL COMPATIBILITY : CG-5 Mount
APERTURE : 279.4 mm (11 in)
FOCAL LENGTH : 2800 mm (110.24 in)
FOCAL RATIO : 10.02
OPTICAL TUBE : Aluminum
EYEPIECE 1 : 40 mm (1.57 in)
MAGNIFICATION 1 : 70 x
STAR DIAGONAL : 1.25
OPTICAL COATINGS : StarBright / XLT
SECONDARY MIRROR OBSTRUCTION : 3.75 in (95.25 mm)
SECONDARY MIRROR OBSTRUCTION BY AREA : 11.6 %
SECONDARY MIRROR OBSTRUCTION BY DIAMETER : 34.1 %
OPTICAL TUBE LENGTH : 24 in (609.6 mm)
OPTICAL TUBE WEIGHTl : 27.5 lb (12.47 kg)
Warranty: 2 years
The largest of the Celestron's SCT OTAs that can be used successfully on the mid-priced German equatorial mounts available, e.g. Celestron CGEM, Skywatcher EQ6 and EQ6 Pro. The Skywatcher HEQ5 will handle the tube assembly for visual use, but may be a little lightweight for serious imaging. This tube assembly is offered as a complete telescope product on the Advanced GT CG5 mount, however, modern imaging requires suitable mounting for ease of tracking, and the CG5 and EQ5 mount are not recommended by us for the C11 tube assembly because of the weight of the tube.
Suitably mounted, the C11 is an excellent observing instrument for deep-sky and planetary. This is the largest SCT tube assembly that can be considered portable rather than transportable. It can be transported by car to a dark sky site or star party in its foam lined carton, or it will sit up quite happily on the front seat of a car with a seat belt around it (author's experience). A good quality 2" star diagonal is a must for this telescope as the use of 2" 40mm and 35mm eyepieces is very rewarding. The Celestron Luminos 31mm, Baader Scopos 35mm and Skywatcher Aero ED 40mm eyepieces are ideal for this telescope. With an Oxygen III filter, the Veil Nebula in Cgynus is an event in itself (even better in the C14 OTA). The reason (apart from aperture) is the successful baffle system in the SCT plus the XLT coatings, diffuse nebula are simply easier to see in greater contrast now.
The C11 is a successful planetary telescope due to its aperture. A larger aperture means that higher magnifications can be used but this depends on the atmospheric stability in any given site. A popular accessory is a binoviewer, this uses a beam splitting prism, and can provide a more stable image when using two eyepieces and two eyes. For planetary imaging, we only have to visit websites such as www.damianpeach.com to see what can be achieved with Celestron larger aperture SCTs.
Photographically it is a diffraction limited 2800mm f/10 telephoto, a 5600mm f/20 telephoto by adding a 2X Barlow, or a 1764mm f/6.3 telephoto by adding the Celestron f/6.3 focal reducer lens.
TipsBudget for the SCT t-adapter, the f/6.3 focal reducer, a 2" star diagonal so 2" eyepieces can be used, a Neutral Density filter or Polariser for the moon, the Celestron dewshield, and the Baader UHC and Oxygen III filters. Don't under-mount this telescope.
- Optical Design
- Schmidt Cassegrain
- 11 inch
- Focal Length
- 2800 mm
- Focal Ratio
- Optical Coatings
- Starbright XLT Coating
- Optical Tube Length (mm)
- 24 inch