Celestron RASA 6 Rowe-Ackermann Schmidt Astrograph OTA
6" Rowe-Ackermann Schmidt Astrograph, 335 mm f/2.2, 16 mm Ø (2.74°) image circle, CG-5 (Vixen-style) 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
152 mm (6")
Focal length
335 mm
Focal ratio
f/2.2
Image circle
16 mm Ø (2.74°)
Usable field
22 mm Ø (3.76°), minimal loss at the edge
Wavelength range
400–700 nm
Spot size
< 1.5 µm RMS across image circle
Off-axis illumination
91% at 8 mm off-axis
Coatings
StarBright XLT
Central obstruction
77 mm (50.7% of aperture)
Cooling
12 V DC MagLev fan
Mechanical and package
Back focus with included camera adapter
17.5 mm (M42 camera thread)
Focuser
Standard Schmidt-Cassegrain focuser
Tube length
500.5 mm
Tube diameter
177.8 mm
Weight
3.8 kg
Dovetail
CG-5 (Vixen-style) dovetail bar
Finderscope
Not included
Included
42 mm (M42) T-thread camera adapter; fan battery pack; filter drawer with 2" clear filter (takes 2" filters, 1.25" adapter included)
