Celestron 8" Rowe-Ackermann Schmidt Astrograph

8" Rowe-Ackermann Schmidt Astrograph (optical tube only).

The new ultra-fast optical tube from Celestron will allow all deep-sky astrophotography enthusiasts to obtain superb wide-field images with maximum depth. The 4-element front lens group is made of rare-earth glass to achieve the best in reducing chromatic aberration and correcting field curvature, coma, and astigmatism.

State-of-the-art XLT coatings allow for light transmission levels approaching T=1. The f/2.0 focal ratio makes it an extremely fast instrument, allowing you to photograph extended deep-sky objects with significantly shorter exposures compared to classic optics. Furthermore, the short focal length often eliminates the need for autoguiding, a major advantage in terms of the additional equipment you have to carry into the field.

As this is an astrograph, Celestron's opticians have designed a system that allows wavelengths in the deep violet and infrared to converge simultaneously on the sensor, while still ensuring a spot size of less than 4.6 µm RMS. This is a significant advantage, considering that many wide-field celestial objects have a large part of their spectrum in the infrared as well. The Celestron 8” RASA tube is compatible with the latest mirrorless cameras and astronomical CCD and CMOS sensors.

The optical design allows for perfect images up to the edge of the field on sensors with a 22mm diagonal, typical of most recent mirrorless cameras. The field is still reasonably corrected for larger sensors, up to a 32mm diagonal. On FX sensors, however, image performance at the edges is lower, with MTF values and vignetting that are not negligible by today's imaging standards. It is not compatible with DSLR cameras.

The instrument is equipped with a newly redesigned focuser with zero image shift, featuring ball-bearing technology. The 8” RASA is also equipped with a fan to speed up the tube's acclimatization and, through the use of special filters, simultaneously draw in air to remove dust from inside the tube.

FEATURES

• Rowe-Ackermann Schmidt optical design
• Aperture 203 mm
• Focal Length 400 mm
• Focal Ratio f/2.0
• Central Obstruction 93 mm (46% of diameter)
• Image Circle 22 mm Ø, 3.15°

Key features

Celestron quality for a reliable and rewarding observation experience.

• Type: Metal Tube
• Diameter (mm): 203
• Material: Metal Tube
• Aperture Ratio: f/2
• Tube structure: Closed Tube

Main technical specifications