Celestron C9.25-A XLT Schmidt Cassegrain OTA
The Celestron C9.25 is more than just a step between Celestron’s 8″ and the 11″ Schmidt Cassegrains. The optical configuration of the C9.25 is unique – by using a longer focal length primary mirror and having a lower magnification secondary produces a flatter field of view at the focal plane and helps to reduce optical aberrations. Using Celestron’s high manufacturing accuracy to make more moderate radii on the C9.25’s optical surfaces results in a better overall image quality. Compared with other Schmidt-Cassegrain systems, the C9.25 offers better contrast and image definition making it especially interesting for detailed lunar and planetary observation.
All optical surfaces are coated with Celestron’s high efficiency StarBright XLT ® multi-layered coating group for brighter images. The Optical Tube has an optimised baffle system which benefits imaging by minimising vignetting at the edges of the field.
The Celestron C9.25-A XLT Schmidt Cassegrain is an extremely versatile telescope. At f/10 prime focus it has a focal length of 2350mm providing excecllent image scale for observing and imaging very small targets. In addition the Celestron f/6.3 focal reducer (available separately) can be used providing a more moderate focal length of 1480mm.
For those interested in imaging at extremely fast apertures, the C9.25 is “Fastar” compatible. The C9.25 OTA is equipped with a removable secondary mirror for fast f/2 CCD imaging. Not only does imaging in the FASTAR configuration allow for exposure times that are 25 times faster than at f/10, but also yields a field of view five times wider. It’s the perfect solution for imaging your favorite wide field objects in a fraction of the time. (FASTAR imaging require a third party lens assembly in place of the secondary mirror).
- 9.25″ Schmidt-Cassegrain Optical Tube Assembly
- 2350 mm focal length (f/10)
- Aluminium Optical Tube
- Celestron’s premium StarBright XLT coatings
- FASTAR compatible secondary
- 25 mm eyepiece included (94x)
- Visual back allows for use with 1.25″ accessories
- 6×30 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 either CG-5 (narrow) or CGE (wide) mounting saddles.
Starbright XLT multicoatings are now standard on all Celestron SCT optical tube assemblies. The process involves the application of high reflectivity multilayer aluminum on the main mirror with a titanium dioxide overcoat for durability plus a unique combination of magnesium fluoride and hafnium dioxide antireflection coatings on both sides of the Schmidt corrector plate. These coatings together with the use of high transmission water white float glass in the corrector plate (instead of conventional soda lime glass) results in markedly improved light transmission.
The benefit of Starbright XLT multicoatings is a visible increase in contrast of subtle details when compared with telescopes using standard multicoatings. The higher light transmission also provides brighter images of faint deep sky targets Across the total visual/photographic spectrum, independent laboratory tests show the new Starbright XLT coatings are 16% brighter overall than previous StarBright coatings.
|Aperture (mm)||234.95 mm (9.25 in)|
|Focal Length||2350 mm|
|Focal Length of Eyepiece (mm)||25mm|
|Magnification of Eyepiece||94 x|
|Highest Useful Magnification||555 x|
|Lowest Useful Magnification||34 x|
|Limiting Stellar Magnitude||14.4|
|Resolution (Dawes)||0.49 arc seconds|
|Light Gathering Power (Compared to human eye)||1127 x|
|Secondary Mirror Obstruction||85 mm|
|Secondary Mirror Obstruction by Diameter||36%|
|Secondary Mirror Obstruction by Area||13%|
|Optical Coatings||StarBright / XLT|
|Optical Tube Length||559 mm|
|Optical Tube Weight||9.1 kg|
Celestron C9.25-A XLT Schmidt Cassegrain (CG-5)
Part Number: 91025-XLT
Celestron C9.25-A XLT Schmidt Cassegrain OTA (CGE)
Part Number: 91027-XLT
Choosing between the CG-5 and CGE Dovetail Bars
The Celestron C9.25-A XLT Schmidt Cassegrain tube assemblies are available with 2 different dovetail plates. You can select either Celestron C9.25-A XLT (CG-5 bar) or Celestron C9.25-A XLT (CGE bar). Choose the appropriate model according to the mount you intend to use.
CG-5 bar (narrow or Vixen style dovetail)
The CG-5 (narrow) dovetail plate has a profile 44mm wide at its base – it fits Celestron mounts including the CG-5, Advanced Series Go-To, Advanved VX and newer CGX* German equatorial mounts. It is also compatible with SkyWatcher EQ5, HEQ5, NEQ6 Pro*, EQ6R Pro* and AZ-EQ6* mounts, Losmandy GM8* and G11* plus many mounts manufactured by Orion, Vixen and iOptron (mounts marked with an * have dual dovetail saddles that accept either narrow or wide dovetail plates).
CGE bar (wide or Losmandy D-Style)
The CGE (wide) dovetail plate has a profile 75mm wide at its base. It fits Celestron mounts including the CGE, CGE Pro, CGEM, and newer CGX and CGX-L German equatorial mounts. It is also compatible with SkyWatcher NEQ6 Pro, EQ6R Pro, AZ-EQ6 and EQ8 mounts. Losmandy GM8 and G11, Software Bisque Paramount MyT, MX+ and MEII plus many mounts manufactured by Orion, Vixen, iOptron and others.
If your mount accepts the wider CGE style bars it is the preferred choice. The wider profile provides a more rigid connection between your telescope and mount compared to the CG-5 dovetail.