The Celestron RASA 8" Rowe-Ackermann Schmidt Astrograph is an incredibly fast f/2 optical system designed for imaging with modern CMOS cameras. The RASA 8" provides a flat field free of optical aberrations across a 22mm field of view, with usable performance up to 32mm making it suitable for APS-C and smaller sized sensors.
Note: the RASA 8" cannot be used with systems requiring filter wheels or large DSLR bodies. Instead, it is recommend to use colour or mono CMOS cameras with a filter drawer. As the focal plane is at the front of the optical system, it cannot be used visually with an eyepiece.
As the RASA 8" is a fast f/2 system, you can use much shorter exposure times than usual to capture faint objects. This combined with the short focal length of 400mm means that you don't need to have super-accurate tracking over extended periods, making the RASA 8" suitable for use on a wide variety of equatorial mounts.
The RASA 8" includes Celestron's Ultra-Stable Focus System which utilizes two sets of precision sealed ball bearings to virtually eliminate lateral movement of the primary mirror when focusing, slewing or tracking.
Building on the legacy of Celestron's Schmidt Cameras of the 1970's, the RASA 8" allows astrophotographers to capture incredible data with minimal exposure times. The 4-element lens group with rare-earth ED glass provide images free from aberrations that are inherent in other types of telescopes.
With an extended spectral range of 390-800nm, the RASA 8" is designed for use with modern cameras that are sensitive to NIR wavelengths in the 700-800nm range. Unlike many telescopes which are only designed for the visual spectrum up to 700nm, this extended range will be well focused in the RASA 8", leading to sharper and brighter images.
The RASA 8" performs best once its optics have reached thermal equilibrium with the ambient air. To aid this, the telescope is equipped with cooling fans which direct air through the tube and around the primary mirror.
Note: it is recommended to only use narrowband filters that are optimized for fast systems such as the or .
Specifications
| Optical design | Rowe-Ackermann Schmidt Astrograph |
|---|---|
| Aperture | 203 mm (8") |
| Focal length | 400 mm |
| Focal ratio | f/2.0 |
| Resolving power | 0.57 arc seconds |
| Image circle | 22 mm, 3.15° |
| Usable field | 32 mm, 4.6° with only minimal performance loss at edge of FOV |
| Light gathering power | 843 times the human eye |
| Central obstruction diameter | 93 mm (46% of aperture diameter) |
| Wavelength range | 390 - 800 nm |
| Spot size | < 4.6μm RMS across image circle |
| Optical coatings | StarBright XLT |
| Off-axis illumination | 93% at 11 mm off-axis |
| Optical window diameter | 46 mm |
| Backfocus with included M42 adapter | 25 mm |
| Backfocus from top of threaded collar | 29 mm |
| Mount attachment | CGE dovetail plate |
| Focuser | Ultra-Stable Focusing System |
| Included connection adapters | M42 x 0.75, C-mount |
| Tube length | 628 mm |
| Tube weight | 7.7 kg |
| Tube diameter | 235 mm |
| SKU | CE-91073 |
Items included
- RASA 8"
- CGE dovetail
- Dew cap
- M42 camera adapter
- C-thread adapter
- Fan battery pack
Filter solutions
Due to the very short backfocus of 29mm from the threaded collar, we recommend the for ZWO ASI cameras. or the .
Usage with Baader UFC
In order to connect ZWO ASI cameras with 6.5mm of backfocus such as the 533, 183 and 294 series, you will need the following pieces:
Usage with Baader FCCT
In order to connect QHY cameras with a 90mm body diameter such as the 268M (pre-June 2023 revision), 294 or 533, you will need the following pieces:
Downloads
 Celestron RASA 8" manual |
For all orders exceeding a value of 100USD shipping is offered for free.
Returns will be accepted for up to 10 days of Customer’s receipt or tracking number on unworn items. You, as a Customer, are obliged to inform us via email before you return the item.
Otherwise, standard shipping charges apply. Check out our delivery Terms & Conditions for more details.
