Celestron Advanced VX 8" RASA Astrograph Telescope

This kit combines the 8” Rowe-Ackermann Schmidt Astrograph (RASA) with the strong-yet-portable Advanced VX (AVX) German equatorial mount. Simply add a mirrorless camera and this package offers everything you need to take spectacular images of wide-field deep sky objects.

RASA Performance Made for Everyone

Capture spectacular wide-field deep sky images in seconds with Celestron’s portable astrograph, the 8” Rowe-Ackermann Schmidt Astrograph (RASA). This incredibly fast f/2.0 system is the perfect companion to today’s color astronomical CMOS cameras, smaller CCD cameras, and mirrorless cameras. Thanks to its fast focal ratio and patented optical design, you can produce sharp, detailed images and, in many cases, skip the autoguider completely. Weighing in at just 17 pounds, it’s easy to transport your 8” RASA to the most remote dark sky locations.

RASA Performance Made for Everyone

The 8” RASA is an imaging telescope that delivers a flat field without optical aberrations for razor sharp stars across a wide field of view. It can capture stunning deep-sky astronomical images without the challenges typically presented by longer focal length instruments at a fraction of the cost of those systems.

The latest addition to the RASA family, this 8” version is a much more portable and affordable version of the heralded RASA 11, which was introduced to much acclaim in 2014. With the 8” RASA joining the lineup, a wider range of astroimagers can enjoy the benefits of the RASA design. It has many of the same thoughtfully designed features as its “big brother” RASA 11, including the integrated air-cooling system, internal filter mount, and sturdy CGE dovetail mounting bar.

Purely designed for imaging, the 8” RASA cannot be used visually. The prime focus focal plane is located at the front of the optical system, so it cannot accommodate a traditional eyepiece.

Shorter Exposure Times and Virtual “Real-Time” Observing

Since it is an F/2.0 optical system, imagers can use shorter exposure times to capture detail in faint objects. When combined with sensitive cameras and the proper “live stacking” software, the 8” RASA can provide an almost real-time observing experience. View images on a computer instantly that are brighter and more detailed than can be seen in much bigger telescopes with the naked eye.

Because shorter exposure times are possible, your equatorial mount won’t need to accurately track over extended periods. The 8” RASA’s relatively short 400mm focal length also lessens equatorial tracking demands. In many cases, autoguiding will not be required. Weighing only 17 lb, this optical tube pairs perfectly with a wide variety of mounts.

Ultra-Stable Focus System

With the launch of the 8” RASA, Celestron unveiled a new focuser design that mitigates lateral movement of the primary mirror when focusing, slewing, or tracking with the astrograph. Focusing is easier, more accurate, and more stable than ever. The key to the Ultra-Stable Focus System is a precision linear ball bearing, which is tested during assembly to ensure optimal results.

Built for Today’s Latest Cameras

Unlike the larger RASAs that work with DSLR and large CCD cameras, the 8” model was designed with color astronomical CMOS cameras, smaller CCD cameras, and mirrorless cameras in mind. The telescope does not work with standard DSLR cameras. It is optimized for sensors with up to a 22mm diagonal, but performs well with sensors up to 32mm diagonal. The APS-C sized sensors used in many mirrorless cameras are a good choice. 42mm full frame sensors will also work, but performance will be poor at the edges of the sensor and field illumination will be reduced. Additionally, we do not recommend pairing RASA 8 with any camera body more than 4” in diameter. See the chart below to determine if your camera is compatible with RASA 8.

Unique Optical Design

RASA’s optical design is patented (US 2016/0299331 A1). The design consists of a Schmidt corrector, primary mirror, lens group, and optical window. The lens group contains 4 elements and utilizes rare-earth elements. Unlike many telescopes that only perform well over the visible spectrum (400-700nm), the 8” RASA’s optics are designed to perform over a wider spectral range, from 400-800nm. This allows more of the light emitted from the astronomical object to be sharply focused in the image.

With many imaging systems, adding an extra piece of flat glass such as a filter does not change optical performance. However, that is not the case with super-fast optical systems like the RASA. Our engineers addressed this by designing the RASA with a removeable optical window, so you can maintain peak optical performance if a filter is added or if a camera has its own optical window. Celestron offers a Light Pollution Imaging Filter designed specifically for the 8” RASA, which mounts in place of the optical window.

All refractive optical surfaces are coated with StarBright XLT coatings, while the primary mirror uses enhanced aluminum coatings. This maintains high light transmission through the entire optical system.

When compared with “Hyperstar SCT” systems, the RASA 8 provides better optical performance and field illumination.

Advanced VX & Tripod

The Advanced VX mount is designed to provide superior performance for smaller telescopes while taking advantage of Celestron’s most advanced technologies: All-Star Polar Alignment, Celestron PWI telescope control software, SkyAlign, and permanently programmable periodic error correction (PPEC).

If you’re an experienced imager, you’ll love taking this portable mount to a dark sky site and enjoying all the conveniences of a larger observatory mount. Or, if you’re new to imaging, Advanced VX will help you get started with the hobby and keep up with your needs for years to come.

Computerized German equatorial mount

The Advanced VX is the smallest of Celestron’s German equatorial mounts. The computerized GoTo capability automatically tracks objects as they move across the night sky. The Advanced VX mount includes ports for a hand control, an autoguider, and 2 AUX ports for optional accessories. The NexStar+ hand control gives you instant access to all the functions your mount has to offer. With automatic slewing and menu descriptions, astronomers of all skill levels can master this mount in just a few observing sessions. The Advanced VX also has an impressive tripod for its class with 2”-diameter steel tripod legs, providing an extra-wide stance for improved stability.

Payload capacity
The payload capacity for the Advanced VX is 30 lb. It offers a sturdy platform for the 8” Rowe-Ackermann Schmidt Astrograph optical tube, even when paired with optional accessories like StarSense AutoAlign, Focus Motor, a finderscope, and a camera. Celestron's payload capacity does not include the weight of the counterweights.

Dual saddle plate
As of early 2019, Advanced VX mounts include a dual saddle plate that accommodates both CG-5 and CGE-style dovetails. Switching between the two saddle plates is as simple as moving the hand knobs into a separate set of holes. You can use your Advanced VX mount not only with the 8” RASA, but virtually any optical tube within Advanced VX’s weight limit. Compatible with Vixen format dovetails 100mm or longer, not compatible with Losmandy D format plates (regardless of plate manufacturer).

Software

Celestron PWI Telescope Control Software
Your Ultimate Astronomy Software Suite

All current Celestron computerized telescopes include Celestron PWI (CPWI), the most advanced astronomy software suite provided with any consumer-grade telescope. Celestron’s experts co-developed CPWI with the engineers at PlaneWave Instruments. The result is an all-in-one solution offering you many of the same features used on PlaneWave’s observatory-class telescopes.

Graphical planetarium interface with PointXP advanced mount modelling allows you to add 100+ points to your alignment model for the most accurate pointing and tracking possible
Ideal for remote observatory setups: save and re-load your alignment and park your scope
Provides a complete ASCOM telescope interface to allow control of the telescope from third party software applications
For more information on CPWI and to see the user interface, click here.

Starry Night Software
Also included with your purchase is a free download of Celestron’s Starry Night Special Edition Software. This advanced software by Simulation Curriculum offers detailed information about celestial objects and helps you plan your next observing or imaging session. The Special Edition software also includes telescope control via your PC.

Accessories Included

The Advanced VX RASA 8 comes complete with a M42 camera adapter, C-thread camera adapter, and fan battery pack.

Specifications:

OPTICAL TUBE INFO:
Optical Design: Rowe-Ackermann Schmidt Astrograph
Aperture: 203mm (8")
Focal Length: 400mm (15.74")
Focal Ratio: f/2.0
Central obstruction diameter: 93mm (3.66") (46% of aperture diameter)
Light Gathering Power (Compared to human eye): 843x
Resolution (Rayleigh): 0.68 arc seconds
Resolution (Dawes): 0.57 arc seconds
Image Circle: 22mm (.86") Ø, 3.15°
Useable field: 32mm (1.26") Ø, 4.6°, only minimal performance loss at edge of FOV
Wavelength range: 400 - 800 nm
Spot size: < 4.6 μm RMS across image circle
Optical Coatings: StarBright XLT
Off-axis Illumination: 93% at 11mm (.43") off-axis
Optical Window: 46mm (1.81") Ø
Back focus with included camera adapter: 25mm (.98")
Back focus from top of threaded collar: 29mm (1.14")
Optical Tube: Aluminum
Optical Tube Length: 628mm (24.7")
Optical Tube Diameter: 235mm (9.3")
Focuser: Ultra-Stable Focusing System
Finderscope: Not included
Optical Tube Weight: 17 lbs (7.7 kg)
Other Features: Air-cooling system, integrated filter mount
Included Items: Advanced VX Equatorial Head and tripod
Accessory Tray
1 x 12 lbs counterweight
NexStar+ Hand Control
DC Power Cable (plugs into cigarette lighter socket)
Dovetail: CGE Dovetail Bar

MOUNT INFO:
Mount Type: Computerized Equatorial
Instrument load capacity: 30 lbs (13.6 kg)
Height adjustment range (includes mount and tripod): 1118mm - 1626mm (44" – 64")
Tripod Leg Diameter: 50.8mm (2") Stainless Steel
Latitude adjustment range: 7° - 77°
Mount Head Weight: 17 lbs (7.71 kg)
Accessory Tray: Yes
Tripod Weight: 18 lbs (8.16 kg)
Weight of Counterweights: 1 x 12 lbs
Slew Speeds: 9 slew speeds - max speed 4°/second
Tracking Rates: Sidereal, Solar and Lunar
Tracking Modes: EQ North and EQ South
GPS: N/A
Dovetail Compatibility: Dual saddle plates (CG-5 and CGE saddle)
Number of Auxiliary Ports: 3 AUX Ports (1 hand control and 2 AUX Ports for optional accessories)
Autoguide Port: Yes
USB Port: Yes, input on Hand Control
Power Requirements: 12V DC 3.5A (tip positive)
Motor Drive: DC servo motors
Alignment Procedures: 2-Star Align, 1-Star Align, Solar System Align, Last Alignment, Quick Align
Periodic Error Correction: Yes
Computerized Hand Control: NexStar+ hand control with LCD display, 19 fiber-optic backlit LED buttons
NexStar+ Database: 40,000+ objects, 100 user defined programmable objects. Enhanced information on over 200 objects
Software: Celestron Starry Night Special Edition Software and SkyPortal App
Total Kit Weight: 47 lbs (21.31 kg)

Solar Warning
Never look directly at the Sun with the naked eye or with an optic (unless you have the proper solar filter). Permanent and irreversible eye damage may result.
Never use your optic to project an image of the Sun onto any surface. Internal heat build-up can damage the optic and any accessories attached to it.
Never leave your optic unsupervised. Make sure an adult who is familiar with the correct operating procedures is with your optic at all times, especially when children are present.

Some items that are showing as in stock are in stock at our holding warehouses, not at the shop. To double check the stock levels at the shop, please contact us on 01909774369 or sales@rothervalleyoptics.co.uk.

The delivery times for most items is 1 - 2 days but again, please double check stock levels on important orders before placing an order via the website.

The delivery costs for courier next day are for mainland UK only. If you live in the Scottish Highlands/Islands, Channel Islands or Northern Ireland, then a shipping surchage will apply. please contact us for prices. Smaller items can still go 1st class via Royal Mail.

Please note that if you are wanting to take advantage of our Saturday and Sunday timed services or next day pre 12 or pre 10:30 services, you MUST check that the stock is here at the shop before placing orders. Also, orders using the Saturday and Sunday services must be placed before 1pm the previous working day. Also, please remember to check that the stock is here at the shop before placing orders. If the stock is not at the shop, we won't be able to ship on any of the timed services. 

Please note International customers will need to contact us for a shipping price prior to ordering via the website. We don't ship all items internationally. It is at our discretion what we ship outside of the UK. This all depends on the size and weight of the items. Please get in touch with us for any postage costs. Please note we do NOT ship telescopes or heavy items outside of the UK. This is due to massive postage costs and problems regarding returns.

If you have any questions regarding stock levels or delivery, please get in touch.

Zygo Interferometer Testing For ED Refractor Telescopes!

We are extremely pleased to announce our Zygo Interferometer is now installed and ready for use! Our experienced staff can test refractor lenses up to 120mm aperture and provide a comprehensive 2 page report showing the optical quality and Strehl ratio, plus much more information. We are using the very latest Zygo MX software to provide a more detailed report compared to other standard reports.

The interferometer is essentially a measuring instrument. Within the interferometer is a calibrated laser that is pointed through the optical test surface, then onto a high quality reference sphere, then back through the test subject then to an internal camera which gives us the measurement on the screen. From this, we can adjust the position of the test optic and the reference sphere to obtain a perfectly calibrated system. The more central the laser to the test optic and then on return, the better and more accurate reading and measurement we can take. This takes a lot of adjustment to get the best results from the optical surface. Once the measurement has been taken, we are provided with a series of results that show the optical quality of the surface plus other information. Continue reading for an explanation of the individual values and you can also see a test report that was done on one of our RVO Horizon 60 OTAs. 

We are offering certain telescopes with a Zygo test at an extra cost. Mainly ED doublets and triplets. All available telescopes with a Zygo test report are listed here. Just select Zygo Test Report from the drop down box at the top of the listing and we will test the optics in house and provide a full 2 page report with your scope. This will show you the optical quality of your telescope optics. We can also offer this service on your refractor telescope. Please get in touch for more details about this. 

At Rother Valley Optics, one thing we pride ourselves on is customer service and quality of our equipment. When we test your telescope, we will ensure that it is of the highest quality otherwise, we will reject the scope under our strict quality control and test another model for your peace of mind. One of the main values to look at when testing a refractor is the Strehl ratio. The higher this number, the higher quality lens you have. At Rother Valley Optics, we will guarantee the highest possible Strehl ratio for your telescope.  We will aim to provide 0.95 Strehl or higher on Takahashi, RVO Horizon, William Optics and many more! Generally, the higher the Strehl ratio, the lower the Astigmatism and Coma meaning a better image quality from your instrument. 

Other measurements such as the PV and RMS are important too. With these measurements, the lower the number the better as it shows less curvature on the lens. The flatter an optical lens, the better it will perform. The PV rating (Peak To Valley) is a measurement from the highest point (Peak) to the lowest point (Valley). From this we get the RMS (Root, Mean, Square). This is a similar figure to the PV and measured exactly the same way. The RMS is basically an average height difference from the PV so again, the lower the better. As you can see form the example below, we measured an RMS of just 0.027 wave which is a very good value.

We also measure the Power with our systems which is essentially the error from the reference sphere to the test optic. The reference sphere we use on our system is a very high quality sphere so the closer to zero the Power, the less error between the 2 elements thus ensuring a higher quality optical surface. 

You will also see some more values such as Astigmatism and Coma. Again, these are measured by the interferometer when we take measurements of the optical surface after adjustment. These are values which ideally would be at 0 but as our test optics are all curved lenses, there will always be astigmatism and coma present. The lower the number, the less of these aberations you will effectively see but with most refractors, you can buy field flatteners which will compensate for the coma anyway. The astigmatisms value is explaining the error between the symmetrical curvature of the lens. Basically, no lens will be perfectly symmetrical, the lower the astigmatism, the more symmetrical the lens surface is. 

Once the Zygo test report has been completed, the optical alignment is thoroughly tested and tuned to ensure they are spot on before they leave us. 

All available telescopes are on the website at the link below and ones we've tested already that are available straight away are also listed.

https://www.rothervalleyoptics.co.uk/zygo-tested-refractors.html

Here is an example of the test what we provide. This was a test on one of our Horizon 60 ED OTA's.

For any questions about this amazing new service, please either call 01909774369 or email sales@rothervalleyoptics.co.uk.

Are you interested in this product but would like to speak to someone with some more information? Simply fill in the form below and we will get back to you as soon as we can!

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