Telescope Optical Tube Assemblies - OTA

The FRA, which stands for "Flatfield Refractive Astragraph", is a refractive astrograph designed for built-in flat field correction. FRA also used in visual observation, this series creates versatile high-quality flat frame images for astrophotography, is the few great telescope of versatile optical tube. Description For easy parameter conversion between different lenses, the first-come of the FRA family features a Petzval-like quintuplet design (two pieces of which are special ED glass) with an aperture of 72mm, a focal length of 400mm and a focal ratio of f/5.6, providing a 44mm image circle. The FRA400 quintuplet astrograph has adopted modern optical design...

Since their inception, Askar FRA series short focal ratio astrograph have been very well received by astronomical amateurs. This year, we launched the FRA300 Pro - the smallest 60mm F/5 Petzval astrograph with the fastest native focal ratio in the FRA series so far, its focal length is 300mm. Description The star is sharp and delicate. At the center of its field of view, the RMS radius can reach 2um. Even a serious user can also be satisfied when it comes to the shape of stars. It performs excellence with full-frame and supports 44mm imaging, which is a rare astrograph...

EdgeHD is an aplanatic, flat field Schmidt-Cassegrain telescope that produces aberration-free images across a wide visual and photographic field of view. The optical system was designed to reduce more than just off-axis star coma; it also provides an astrograph-quality flat focal plane all the way to the edge of the field of view. Description True Astrograph Quality Many optical designs that advertise themselves as "astrographs" actually only produce pinpoint stars across a curved focal plane. While this may be acceptable for some visual observing, stars will appear out of focus at the edge when used with the flat chip sensor...

Sharpstar 76EDPH is the second arrival to the Sharpstar EDPH family. It has caught the spotlight for its aesthetic and streamline appeal since its entry to the market. Sharpstar 76EDPH features triplet air-spaced lens structure, including an ED(extra-low dispersion) glass ensuring an pleasing application in both visual observation and astrophotograph. This can effectively eliminate the chromatic aberration thus produce more detailed and higher-contrast images. Description The aperture size is 76mm, and the focal length is 418mm, so the focal ratio is f/5.5. The whole length of the main tube is only 332.9mm when used with the dew shield contracted. Its...

Since the Sharpstar 61EDPH astrograph was launched, it has garnered a worldwide cult following. Not blinded by the accomplishment and applause, Sharpstar, humble and prudent, is willing to hear different voice from our customers. Take the advantage of the already-existing technology and its solid-performing precursor, Sharpstar 61 EDPH II, more advanced and universal, finally hit the market. Description The upgraded 61EDPH II has inherited the strengths from its predecessor. It features triplet air-spaced APO lens design, and one of which is an ED(extra-low dispersion) glass, permitting a superb performance in chromatic-aberration correction, suitable for both visual observation and astrophotograph. The...

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 colour 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. Description RASA Performance Made for Everyone The 8" RASA is an imaging telescope that delivers a flat...

Advanced Coma-Free LX200 Optical Tube comes with Meade's Ultra-High Transmission Coatings (UTHC), Oversized Low-Expansion Borosilicate Primary Mirror, Schott Borofloat Glass Corrector Plate, Diffraction Limited Optics, Losmandy-style dovetail, and Dust Cover. Description The Advanced Coma-Free (ACF) optical system has brought the highest level of optical performance well within the reach of most amateurs. Using the Meade exclusive design, ACF optics achieve aplanatic performance - with a flatter field, reduced astigmatism and eliminated diffractions spikes. Coupled with Meades Ultra-High Transmission Coatings (standard on all LX200-ACF systems), you have the ultimate in premium optics. All LX200 models feature a primary mirror locking mechanism,...

Sky-Watcher's Evostar apochromatic doublet refractors are the perfect blend of superior extra-low dispersion glass and affordability. The Evostar refractor lens assembly utilizes a proprietary combination of matched lenses, delivering tack-sharp stars with charcoal-black, contrast-rich skies. All ED glass elements are fluorite-based and feature our proprietary Metallic High-Transmission Coatings (MHTC), virtually eliminating all false color while the internal baffle helps prevent stray light from affecting your photography. Like the optics, the tube is beautifully crafted using aluminum and finished with a black diamond metal-flake finish. Description Using a doublet refractor instead of a triplet has some advantages: less glass means less...

Our Take on the SharpStar 94 EDPH The 94EDPH is the largest telescope in the SharpStar EDPH family. Its aperture is 94mm and the focal length is 517mm, yielding a fast focal ratio is f/5.5. The 94EDPH is designed with triplet air-spaced APO lens structure, including two pieces of ED (extra-low dispersion) glass. This allows the astrograph to produce more sharp, flat images. With its compact form factor, fantastic appearance, and superb quality, the SharpStar 94EDPH is a great telescope for visual observation and sophisticated astrophotography. Description SharpStar 94EDPH uses the same reducer as the 76EDPH, making it easy to switch between the 76 and 94 for imaging different targets....

The Orion ShortTube 80 Refractor Telescope Optical Tube Assembly is ideal for use as a dedicated guide scope for guided astrophotography pursuits. The fast f/5 achromatic optics provide a wide field of view that makes guide star acquisition a breeze. Its a-metal tube features a rack-and-pinion focuser with drawtube tension adjustment and a molded-in dovetail finder scope base that accepts optional Orion finder scopes. Weighing we under 3 lbs., the ShortTube 80 OTA can easily be added to virtually any astrophotography rig without exceeding your equatorial mount's payload capacity. Description The ShortTube 80 OTA also excels as a wide-field visual...

Sky-Watcher's Evostar apochromatic doublet refractors are the perfect blend of superior extra-low dispersion glass and affordability. The Evostar refractor lens assembly utilizes a proprietary combination of matched lenses, delivering tack-sharp stars with charcoal-black, contrast-rich skies. All ED glass elements are fluorite-based and feature our proprietary Metallic High-Transmission Coatings (MHTC), virtually eliminating all false color while triple-baffles prevent stray light from affecting your photography. Like the optics, the tube is beautifully crafted using aluminum and finished with a black diamond metal-flake finish. Description Using a doublet refractor instead of a triplet has some advantages: less glass means less weight, less weight...