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RASA 8 "- Rowe-Ackermann Schmidt Astrograph

8-inch f / 2.0

Flat image field, free from optical errors such as field curvature, coma, astigmatism and chromatic aberration over the entire field of an APS-C sensor

NEW ultra-stable focusing system - six sealed precision ball bearings prevent image shifting

Integrated air cooling system -12V DC MagLev fan with dust protection reduces the cooling time and ensures an optimal airflow

Internal filter holder - integrates a light pollution filter seamlessly into the light path

CGE dovetail prism rail (3 "Losmandy standard)

extended spectral range of 390-800 nm, so that a brighter overall signal can be recorded



RASA 8 "- Rowe-Ackermann Schmidt Astrograph
Celestron's transportable Astrograph, the 8 "Rowe-Ackermann Schmidt Astrograph (RASA), can take spectacular deep sky wide-angle images in seconds. This incredibly bright f / 2.0 system is the perfect telescope for modern astronomical CMOS color cameras, smaller CCD cameras and mirrorless cameras.

Thanks to the large opening ratio and the patented optical design, you can create sharp, detailed images and in many cases completely do without an autoguider. Weighing just 7.7 kg (17 pounds), it is easy to transport the 8 "RASA to the most remote locations.

RASA service for everyone
The 8 "RASA is a photography-only telescope that provides a flat field of view with no optical aberrations and thus shows extremely sharp stars over a large field of view. It enables astronomical images with an impressive" depth "and avoids the problems that typically arise Instruments with a longer focal length (and a slower aperture ratio) occur.

The latest addition to the RASA family with an 8 "opening is a much more portable and affordable version of the RASA 11, which was launched with great success in 2014. With the 8" RASA, the advantages of the RASA design can now be used by a large number of astrophotographers , It shares many features with its "big brother" RASA 11, including the integrated cooling system, the internal filter holder and the robust CGE dovetail mount.

The 8 "RASA is designed for photography only and cannot be used visually. The focal plane is located on the front of the optical system so that the telescope cannot accommodate a conventional eyepiece.

Shorter exposure times and virtual "real time" observation
Because it is an optical f / 2.0 system, astrophotographers can use shorter exposure times to capture details in weak objects. In combination with sensitive cameras and the right "live stacking" software, the 8 "RASA also enables almost live observations: You can view and stack the images immediately on a computer, making them brighter and more detailed than with the naked eye - even compared to much larger telescopes!

Since shorter exposure times are possible, your mount does not have to track with high precision over longer periods of time. The relatively short focal length of 400 mm of the 8 "RASA additionally reduces the requirements for tracking. In many cases, autoguiding is not necessary. With a weight of only 7.7 kg (17 pounds), this telescope fits perfectly with a large number of commercially available mounts.

Ultra stable focusing system
With the introduction of the 8 "RASA, Celestron is introducing a new focusing mechanism that reduces the play of the primary mirror when focusing, panning or tracking the astrograph. Focusing is easier, more precise and more stable than ever. The key to this ultra-stable focusing system are two groups of Precision bearings that are precisely aligned and tested during assembly to achieve optimal results.

Unique optic design
The patented RASA design (US 2016/0299331 A1) consists of a Schmidt plate, primary mirror, lens group and optical window. The lens group consists of four elements and uses rare earths. In contrast to many other telescopes, which only perform well in visible light (400-700nm), the 8 "RASA is designed for a larger spectral range, from 390-800 nm. In this way, more light from the sky objects can be collected and sharply imaged ,

With many optical systems, it does not matter for the image quality whether another flat glass such as a filter is used. The situation is different with extremely bright systems like the RASA. Our developers have solved this problem by providing the RASA with an optical window that can be removed and replaced with a filter. In this way, the image quality remains at the highest level even if you use a filter or the camera has its own optical window. Celestron offers a filter against light pollution, which was specially developed for the 8 "RASA and which replaces the optical window.

All light-refractive optical surfaces are StarBright-XLT-coated, the main mirror has an improved aluminum coating. This ensures high transmission for the entire system. Compared to the HyperStar system for Schmidt-Cassegrains, the RASA 8 delivers better optical performance and superior illumination.

Developed for the most modern cameras
In contrast to the larger RASAs, which are optimized for DSLR and large CCD cameras, the 8 "model was developed for astronomical CMOS color cameras, smaller CCD cameras and mirrorless cameras. The telescope does not work due to the available back focus with commercially available DSLR cameras It is optimized for sensors with a diagonal of up to 22 mm and still offers good performance with sensors with a diagonal of up to 32 mm The sensors used in many mirrorless cameras are in APS-C format A good choice: 42mm full frame sensors work in principle as well, but the performance at the edges of the sensor is poor and the field lighting is reduced.We also do not recommend the RASA 8 with a camera housing with a diameter of more than 10cm combine.

You can use the following table to determine whether your camera is compatible with RASA 8.

Camera compatible with RASA 8? Adapter required
Astronomical CMOS / CCD camera with C-Mount Yes C-Mount adapter (included)
Astronomical CMOS / CCD camera with M42 threaded connection Yes M42 adapter (included in delivery) with M42 intermediate ring (not included in delivery)
Astronomical CMOS / CCD camera with different connection Yes User-defined camera adapter
Mirrorless Canon with APS-C sensor Yes Camera adapter RASA 8 for Canon system cameras (# 820774, available separately)
Mirrorless Sony with APS-C sensor Yes Camera adapter RASA 8 for Sony system cameras (# 820773, available separately)
Mirrorless Canon with full frame (42mm) sensor Yes, but not optimized over the entire sensor. Camera adapter RASA 8 for Canon system cameras (# 820774, available separately)
Mirrorless Sony with full frame (42mm) sensor Yes, but not optimized across the entire sensor. Camera adapter RASA 8 for Sony system cameras (# 820773, sold separately)
DSLR No -

GENERALLY
MANUFACTURER Celestron
ITEM NUMBER (#) 822252
WEIGHT (KG) 7.7
OPTICS
TELESCOPE SERIES RASA
OPTICAL DESIGN RASA
OPENING (MM) 203 mm
FOCAL LENGTH 400 mm (15.74 ")
Aperture ratio f / 2.0
IMAGE FIELD 22 mm (.86 ") Ø, 3.15 °
BACKFOKUS 29mm (24.7 ") from the front lens group / thread attachment, 25mm (1.14") from the camera adapters supplied
COMPENSATION StarBright XLT
LIGHT COLLECTION ASSETS (FOR HUMAN EYE) 843x
USEFUL FIELD 32 mm (1.26 ") Ø, 4.6 °, only minimal power loss at the corner of the image field
RESOLUTION (RAYLEIGH) 0.68 arcseconds
WAVELENGTH RANGE 390 - 800 nm
RESOLUTION (DAWES) 0.57 arcseconds
SPOT SIZE <4.6 μm RMS across the image circle
OBSTRUCTION 93 mm (3.66 ") (46% of opening)
TUBE (MATERIAL) Aluminum
TUBE LENGTH 628 mm (24.7 ") length | 235 mm (9.3") diameter
TUBE WEIGHT 17 lbs (7.7 kg)
SPECIAL FEATURES Air cooling system, integrated filter holder
MOUNT
INCLUDED ACCESSORIES
FOCUSER Ultra stable focusing system
VIEWFINDER Not included
INCL. ACCESSORIES M42 camera adapter, C-mount camera adapter, battery holder for fans