Outfitted with a large aperture, long effective focal length, and their proprietary StarBright XLT optical coatings, the Celestron C9 1/4-A XLT 9.25" f/10 Schmidt-Cassegrain Telescope provides power and portability. The coating system consists of anti-reflection coatings on the corrector plate, highly reflective index mirror coatings, and low-absorption/high-transmission glass components to ensure that the maximum amount of light is gathered and transmitted to your eye. This system ensures bright and clear high-contrast images with accurate color rendition across the entire visual spectrum without visible distortion at the edges. Celestron includes a standard 1.25" visual back to accept eyepieces and accessories such as the 25mm eyepiece and 90° diagonal supplied with the optical tube assembly (OTA). This OTA is offered here without a mount or tripod for users who already have a support system. Just ensure the mount's payload capacity exceeds 20 pounds to safely carry the weight and that the mount has a Losmandy-style saddle to match the OTA's CGEM mounting plate.
- 9.25" (235mm) aperture
- f/10 focal ratio
- 2350mm effective focal length
- Schmidt-Cassegrain design optical path
- StarBright XLT optical coatings
- Resolution: 0.59 arcsec (Rayleigh); 0.49 arcsec (Dawes)
- Secondary mirror obstruction: 3.35" (85mm); 36% by diameter; 13% by area
- Maximizes light transmission through the optical path
- Improves color rendition, contrast, sharpness, resolution, and brightness
- Broadband system provides flat wavelength transmission across the entire visual spectrum
- Multi-layer mirror coatings with layers of aluminum, SiO2 (quartz), and TiO2 (titanium dioxide)
- 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
- High-transmission water white glass corrector plate limits light loss due to internal absorption
- Optical tube only; a mount and tripod are required for proper use
- Comes with an attached CGEM dovetail plate, which is compatible with all Celestron and select third-party saddles; the plate can be unscrewed
- Mount must have a payload capacity of over 20 lb to safely support the OTA
- Standard threads for Schmidt-Cassegrain telescope optical tubes
- 1.25" eyepiece holder accepts 1.25" eyepieces and accessories
Eyepiece:
- 1.25" diameter barrel
- Accepts most 1.25" astronomical filters
- 25mm focal length produces 94x magnification
Diagonal:
- 1.25" diameter barrel
- 90° angle places the head in a comfortable viewing position when the scope is aimed at or near the zenith
- Star diagonal corrects view horizontally, but not vertically
Finderscope:
- 6x magnification
- 30mm aperture
- Mounting bracket included