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Starbright XLT multicoated optics: This advanced optical coatings package includes vacuum-deposited multilayer high reflectivity aluminum mirrors. They are enhanced with titanium dioxide for maximum reflectivity and overcoated with a protective layer of silicon monoxide (quartz) for long life.

A unique combination of magnesium fluoride and hafnium dioxide antireflection coatings is vacuum-deposited on both sides of the Schmidt corrector lens for maximum light throughput and contrast. The corrector lens itself is made of high transmission water white float glass instead of the conventional soda lime glass (which has 3.5% lower transmission than water white glass) that’s used in other telescopes.

Starbright XLT multicoatings give you higher light transmission for brighter deep space images and shorter exposure times during CCD and 35mm photography. Across the total visual/photographic spectrum from 400nm to 750nm, independent laboratory tests show the new Starbright XLT coatings are 16% brighter overall than even the original industry-standard Starbright multicoatings. The XLT coatings also visibly increase the contrast on subtle lunar, planetary, and nebula details when compared with a scope with standard multicoatings.

Hand-figured optics: Hand figuring the optical system is a complex optical procedure done on a commercial basis only by Celestron. Four separate optical tests are made on every set of Schmidt-Cassegrain optics, using a double-pass laser autocollimator – an Airy disc inspection, a test for spherical aberration by examining the diffraction images on both sides of focus, a Ronchi grating test, and a knife edge test. A skilled optician evaluates these tests, and then fabricates a precision pitch lap and delicately hand polishes the secondary mirror to smooth the optical figure and reduce any small residual zonal defects to vanishingly small levels. Done a few strokes at a time, and testing constantly to evaluate their effect, this final hand-figuring can take hours. But, when it is finished, the optical performance makes every tedious hour of handcrafting well worth the effort.

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