Celestron 8" RASA Imaging Kit - 91079

The Celestron RASA 8 Imaging Kit includes the 8" RASA OTA, an Ha/Hb/OIII Imaging Filter specifically made for the RASA 8, and a Light Pollution Filter, also made to fit the RASA 8".  Buying this RASA 8 Imaging Kit will save you $$$ over purchasing them separately! Read about each of the components below, starting with the star of the show, the Celestron RASA 8 OTA!

Celestron 8" Rowe-Ackermann Schmidt Astrograph
Optical Tube Assembly

• Flat image field free of optical aberrations like field curvature, coma, astigmatism, and chromatic aberration across an entire APS-C sensor

• NEW Ultra-Stable Focus System – six precision sealed ball bearings virtually eliminate image shift

• Integrated air cooling system –12V DC MagLev fan reduces cooldown time and provides optimal air flow while filtering out dust

• Internal filter mount – seamlessly accommodates a Light Pollution Imaging Filter into the optical path

• CGE dovetail mounting rail

• Performs over a wider spectral range than most telescopes, from 390-800 nm, so more of the light passing through the astrograph is in sharp focus

• Wider spectral range means brighter image results with your digital camera

The 8" Rowe-Ackermann Schmidt Astrograph (RASA) from Celestron, is a cost-effective optical system for wide field astroimaging. It offers unprecedented value in aperture, speed, field of view, and optical performance. The RASA design has a convenient external prime-focus image capture location with a flat focal plane, providing small spot sizes to the edge of a wide field. The result is images that are free of optical defects like field curvature, off-axis coma, or astigmatism. RASA 8" has an ample back-focus distance of 25 mm which accommodates a wide variety of imaging sensors.

Some Information About the RASA Technology:

Celestron's 8" Rowe-Ackermann Schmidt Astrograph (RASA’s) optical design is patented (US 2016/0299331 A1). The design consists of a Schmidt corrector, spherical 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 nm-700 nm), the 8” RASA’s optics are designed to perform over a wider spectral range, from 390 nm-800 nm. This allows more of the light emitted from the astronomical object to be sharply focused in the image. Also better spectral matching to silicon array sensors.

With many imaging systems, adding an extra piece of flat glass such as a filter may not affect the optical performance. However, that is not the case with super-fast optical systems like the RASA. Celestron's engineers addressed this concern by designing the RASA with a removeable optical window. This means you can maintain peak optical performance if a filter is added or if a camera has its own optical window. Simply remove the flat window and replace it with a Celestron filter. Celestron offers a Light Pollution Imaging Filter designed specifically for the 8” RASA, which replaces that 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 a “Hyperstar SCT” system, the RASA 8 provides better optical performance and field illumination.

8" Astrograph Scope Description:

Capture spectacular wide-field deep sky images in seconds with Celestron’s new 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 often, you can eliminate the need for using an autoguider completely because of the fast exposures. Weighing in at just 17 pounds, it’s easy to transport your 8” RASA from Celestron to the most remote dark sky locations.

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. This astrograph 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 has many of the same thoughtfully designed features as its “big brother” the RASA 11", including the integrated air-cooling system, internal filter mount, and sturdy CGE dovetail mounting bar.

As a typical astrograph design, this scope was purely designed for imaging, hence the 8” RASA cannot be used visually. The prime focus focal plane is located near the front aperture of the optical system, so it cannot accommodate a traditional eyepiece. Since it is an F/2.0 optical system, imagers can use shorter exposure times to capture detail in faint objects. 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 400 mm focal length also lessens the demand for equatorial tracking accuracy. In many cases, autoguiding will not be required. Weighing only 17 lb, this optical tube pairs perfectly with a wide variety of mounts. Celestron has 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. This Ultra-Stable Focus System uses two sets of precision bearings that are precisely aligned and tested during the assembly process to ensure optimal focus results.

Note that the 8” model RASA 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 which have up to a 22 mm diagonal, but performs well with sensors up to 32 mm in diagonal. The APS-C sized sensors used in many mirrorless cameras are a good choice. 42 mm full frame sensors will also work, but performance will be poor at the edges of the sensor and field illumination will be reduced. Additionally, it is not recommended to pair 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.

Camera Compatibility

RASA 8 Specifications:

Celestron Ha-Hb-OIII Imaging Filter for the 8 RASA

• This is a Celestron Ha-Hb-OIII Imaging Filter for the Rowe-Ackermann 8 (RASA) Astrograph

• Enhance imaging of nebulae with your 8” Rowe-Ackermann Schmidt Astrograph by blocking light pollution, improving image contrast, and darkening the sky background

• This filter transmits only the key Hα-Hβ-OIII wavelengths from emission nebulae, providing high contrast that yields better images

• This filter selectively blocks wavelengths of light from sources of light polluted skies and natural sky glow

• Unlike similar filters with narrower bandpasses, this filter was engineered specifically to work with RASA’s fast f/2 optics

• Fits into the 8” RASA’s integrated filter mount, maintaining peak optical performance

• Optically flat surfaces free of defects, made with Schott glass with anti-reflection coatings

The Celestron Ha-Hb-OIII Imaging Filter made especially for the Rowe-Ackermann 8 (RASA) Astrograph will let you bring out the best in your nebulae astroimages with the H-alpha H-beta OIII (Hα-Hβ-OIII) Imaging Filter. This specialized filter allows high transmission of light from emission nebulae while blocking light pollution, helping to make your images appear with better detail off the black sky background with superior contrast.

This Imaging Filter takes advantage of the fact that many sources of light pollution have relatively discreet emission spectra; they emit primarily at specific wavelengths of light. By strategically blocking these “bad” wavelengths, the filter essentially eliminates the effect of light pollution while letting the “good” wavelengths of light associated with the emission nebula pass through to a camera. You’ll notice much higher contrast in your images immediately, even if imaging from your light polluted backyard! And since the transmission at the key wavelengths you want to image from nebulae is so high, the nebulae will not be dimmed—but the unwanted background will be blacker.

The Hα-Hβ-OIII Imaging Filter for the 8” RASA is perfect for imaging emission nebulae like the North America Nebula (NGC 7000), Lagoon Nebula (M8), Orion Nebula (M42), and the Carina Nebula (NGC 3372). The imaging filter transmits key Hα-Hβ-OIII wavelengths which are most common from the celestial emission nebulae, and that will then produce high contrast for emission nebulae.

NOTE: The transmission for the Hα-Hβ-OIII Imaging Filter is 85% or greater at key wavelengths (486 nm, 496 nm/501 nm, 656 nm) and less than 0.5% transmission elsewhere. The Hα-Hβ-OIII Imaging Filter for the 8” RASA is a narrowband filter that blocks much of the visible spectrum and only allows those specific wavelengths through. Because of this, it will NOT work well on broadband emission objects, such as galaxies and star clusters.

Ha/Hb/OIII Filter Specifications:

Celestron Light Pollution Imaging Filter For 8" RASA

• Enhance your 8” Rowe-Ackermann Schmidt Astrograph (RASA) by blocking light pollution, improving image contrast, and darkening the sky background

• This filter selectively blocks wavelengths of light from sources of light pollution, such as streetlights, but not broad regions of the spectrum where the optical information you wish to capture is located

• Fits into the 8” RASA’s integrated filter mount, maintaining peak optical performance

• Does not block wavelengths associated with emission nebulae, keeping your nebula images bright and detailed

• Optically-flat surfaces free of defects, constructed of Schott glass with anti-reflection coatings applied on both surfaces

Light pollution in the night sky can significantly degrade contrast in astronomical images. This is especially true when using very fast telescopes like the 8” RASA because the sky background saturates very quickly. The “noise” of the light pollution overwhelms the “signal” from the celestial object you are imaging, making it difficult to get the most detailed image. The Light Pollution Imaging Filter for the 8” RASA remedies this by blocking light pollution while transmitting light from deep-sky objects. The result is bright, detailed objects that pop off the black sky background with superior contrast.

The Light Pollution Imaging (LPI) Filter for the 8” RASA blocks light from some of the most common sources of light pollution between 400-700nm (i.e., the visible spectrum), including high- and low-pressure sodium-vapor streetlights, mercury-vapor streetlights, and natural airglow caused by oxygen in the atmosphere. Unlike some light pollution filters, the LPI filter blocks only specific areas of the spectrum instead of wide regions. This helps to maintain image brightness and color balance. In addition, specific wavelengths associated with emission nebulae, such as H-α(656nm), H-β (486nm), OIII (496nm and 501nm), and SII (672nm), are highly transmitted, ensuring minimal loss of image brightness for those objects.

Fortunately, many sources of light pollution have relatively discreet emission spectra; they emit primarily at specific wavelengths of light. By strategically blocking these wavelengths, the filter greatly reduces the effects of light pollution without degrading overall image quality.

Each filter comes with a plastic storage case to safely store the filter or the placeholder-glass that came with your RASA when not in use. You will also receive a spectral transmission test graph unique to your specific unit, verifying its performance.

RASA 8 LPR Filter Specifications: