Celestron RASA 11 V2 Rowe-Ackermann Schmidt Astrograph OTA
11" Rowe-Ackermann Schmidt Astrograph, 620 mm f/2.2, 43.3 mm Ø (4.0°) image circle, CGE dovetail.
The Rowe-Ackermann Schmidt Astrograph (RASA) is a dedicated imaging telescope: the camera sits at the front of the tube, at prime focus, giving an extremely fast focal ratio and a flat, colour-corrected field. Exposures are a fraction of those needed at f/7–f/10, and short exposures often make autoguiding unnecessary. Imaging only, not for visual use. Check that your camera's body is small enough for the front-mounted position (dedicated astro CMOS cameras are ideal; most DSLRs are not suitable).
Optical
Optical design
Rowe-Ackermann Schmidt Astrograph (RASA)
Aperture
279 mm (11")
Focal length
620 mm
Focal ratio
f/2.2
Image circle
43.3 mm Ø (4.0°)
Usable field
52 mm Ø (4.8°), minimal loss at the edge
Wavelength range
400–700 nm
Spot size
< 4.4 µm RMS across field
Off-axis illumination
83% at 21 mm off-axis
Coatings
StarBright XLT
Central obstruction
114 mm (41% of aperture)
Optical window
68 mm Ø
Cooling
Ventilation fan; dual dovetail bars
Mechanical and package
Back focus with included camera adapter
55 mm with included adapter; 72.8 mm from top of threaded collar
Focuser
Ultra-Stable Focus System
Tube length
838.2 mm
Tube diameter
330.2 mm
Weight
19.5 kg
Dovetail
CGE dovetail bar
Finderscope
Not included
Included
42 mm (M42) T-thread camera adapter; 48 mm camera adapter; dust cover; fan battery pack
