For the intermediate visual observer and beginning astroimager the Advanced VX 6” SCT is the most affordable Schmidt-Cassegrain telescope on a solid GoTo mount. The Schmidt-Cassegrain optical design is ideal for imagers and visual observers looking for a telescope that is much more portable than the reflector or refractor. The Schmidt-Cassegrain design also eliminates chromatic aberration making it a good choice for entry-level astroimaging. About the Mount The new Advanced VX mount was specifically designed to provide optimum imaging performance for smaller telescopes. Now your smaller telescope can take advantage of All-Star Polar Alignment and autoguider support. You’ll be able to track through long exposures using permanently programmable periodic error correction. Image across the meridian without doing a meridian flip so you can seamlessly image the best part of night sky. Advanced VX features significantly larger base castings than our previous design improving stability under heavier loads. Improved motors offer more torque and can handle slight load imbalances with ease. 6” (150mm) f/10 Schmidt-Cassegrain includes StarBright XLT coatings for better light transmission 40% more light gathering than a 5” telescope. Integer gear ratios and permanently programmable Periodic Error Correction eliminates recurring track errors from the worm gear. Autoguider port for long exposure imaging New motors offer improved tracking performance & provide more power to overcome load imbalances Updated industrial design offers more rigidity less flexure and improved aesthetics New design allows viewing or imaging across the meridian without interference from the motors housings Improved latitude range. Can be used between 7 – 77 degrees latitude. NexStar+ hand control offers multiple language programming (English French Italian German Spanish) About Celestron Schmidt-Cassegrain Telescopes Celestron’s excellent Schmidt-Cassegrain telescopes are compact and portable and represent the best all-purpose design for a wide variety of uses from terrestrial and deep sky viewing to astrophotography. Catadioptrics use a combination of mirrors and lenses to ""fold"" (reflect) the light path and form an image. In a Schmidt-Cassegrain the light enters through a thin aspheric Schmidt correcting lens. It then strikes the spherical primary mirror. It is reflected back up the tube and intercepted by a small secondary mirror which reflects the light out an opening in the rear of the instrument where the image is formed at the eyepiece. Catadioptrics are the most popular and most modern type of telescope optical design and are marketed throughout the world in 3.5"" and larger apertures. Catadioptric telescopes combine the practical advantages of lenses and mirrors while eliminating their disadvantages. They offer the clarity and contrast of refractors with the low aberration of reflectors. Catadioptrics have an average focal ratio of f/10 which is wide enough for all types of photography. They are also easier to maintain because all optical elements are solidly mounted and rigidly collimated. Catadioptric telescopes provide the best possible combination of light gathering power long focal length portability and affordability. Schmidt-Cassegrain Advantages Very versatile best all-purpose telescope design Combines the optical advantages of both lenses and mirrors while eliminating their disadvantages Excellent optics and razor sharp images over a wide field Excellent for deep sky observing and astrophotography as well as terrestrial viewing Very good for lunar planetary and binary star observing Focal ratio generally around f/10 it also has the best near focus capability of any type of telescope Closed tube design reduces image-degrading air currents Extremely compact and portable Easy to use durable and virtually maintenance free Large apertures at reasonable cost and less expensive than equivalent aperture refractors More accessories available than with other types of telescopes Schmidt-Cassegrain Disadvantages More expensive than Newtonians of equal aperture Slight light loss due to secondary mirror obstruction compared to refractors The Maksutov-Cassegrain is similar to the Schmidt-Cassegrain with essentially the same advantages and disadvantages. It uses a thick meniscus correcting lens with a strong curvature and a secondary mirror that is usually an aluminized spot on the corrector. Celestron All-Star Polar Alignment Technology All-Star Polar Alignment TechnologyGerman Equatorial Mounts (GEM) have long since been recognized as the mount of choice for astrophotography. Needing to track in only one axis for long exposures; adjustable counterweights and tube position for perfect balance the GEM has few short comings when it comes to imaging. In order to do long-exposure astro-imaging an equatorially aligned telescope is needed to allow your telescope to properly track the motion of the sky. However accurate tracking still depends on an accurate polar alignment. Even with a visible star very near the North Celestial Pole (NCP) the true celestial pole can be a very elusive place to find without assistance. Now select Celestron mounts can utilize a new innovative Polar alignment procedure called All-Star™. All-Star allows users to choose any bright star while the software calculates and assists with polar alignment. Here's how it works. Once your telescope is aligned with two bright star All-Star allows you to choose any bright star listed in the NexStar hand control to assist in accurately aligning your telescope's mount with the North Celestial Pole. Using the telescope's Sync function the mount is able to point and center a bright star with a high degree of accuracy. Once centered the mount will point the telescope to the exact position that the star should be if the mount were precisely polar aligned. By simply adjusting the mounts altitude and azimuth controls to re-center the star in the center of the eyepiece you are actually moving the mounts polar axis to the exact position of the North Celestial Pole. FAQ Can I use Polaris to polar align my telescope?Since Polaris is very close to the NCP and not very bright it is actually not a recommended star for the ""All-Star"" method. The advantages of being able to use stars other than Polaris are two fold: Polaris is not always visible. So not only can you use a variety of other stars but they are also brighter and more prominent.The star you choose will be farther away from the NCP thus allowing for greater accuracy when centering the star in your eyepiece. Which stars are best to use for polar aligning?For best results choose a bright alignment star that is near the Meridian preferably close to the celestial equator. Try to avoid stars that are close to the west/east horizon or directly overhead because they can be more difficult to center using the mount's altitude and azimuth controls. Also stars too near the celestial pole are less accurate than those further away. Will I lose my alignment after I polar align?No the mount will retain its alignment but some amount of accuracy may be compromised depending on how much the mount has been moved during polar alignment. Although the telscopes tracking may be very good pointing accuracy may need to be improved especially if you are trying to located small objects on a ccd chip. What are the steps to polar align my telescope using ""All-Star"" polar alignment? Align the telescope with the sky using the ""Two-Star Alignment"" method. Select a suitable bright star from the Hand Control's database and slew the telescope to the star. Press the Align button and select Polar Align => Align Mount from the list. The telescope will then re-slew to the alignment star and ask you to center it in the eyepiece in order to ""Sync"" on the star. The telescope will slew to the position that the star should be if it were accurately polar aligned. Use the mounts altitude and azimuth adjustments to place the star in the center of the eyepiece and press the Align button. Update the telescope's star alignment if necessary.