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Features of this Telescope’s Schmidt-Cassegrain Optical System . . .

• Oversized primary mirror: The diameter of the primary mirror of each LX90LNT is larger than the diameter of the Schmidt corrector lens at the front of its optical tube that admits the light. The primary mirror of the 8” scope is actually 8.25” in diameter, compared to the 8” diameter of the corrector lens. The 10” primary is 10.375” in diameter, and the 12” primary is 12.375”. Oversizing the primary mirror in this way gives you a wider fully-illuminated field than a conventional SCT whose corrector and primary mirror are the same size. The result is a gain of 5% to 8% more off-axis light available to your eye or camera, depending on the telescope.

• Fully-multicoated UHTC (Ultra High Transmission Coatings) optics: The Pyrex primary and secondary mirrors are vacuum-coated with aluminum, enhanced with multiple layers of titanium dioxide and silicon dioxide for increased reflectivity. These multicoatings are then overcoated with a protective layer of silicon monoxide (quartz) for long life.
      A series of anti-reflective coatings of aluminum oxide, titanium dioxide, and magnesium fluoride are vacuum-deposited on both sides of the water-white float glass Schmidt corrector plate. These antireflection multicoatings provide a high 99.8% light transmission per surface, versus a per-surface transmission of 98.7% for standard single-layer coatings. Overall light throughput (the amount of light collected by the objective lens that actually reaches your eye or camera) is approximately 89% at the Cassegrain focus.
      UHTC multicoatings provide a 15% increase in light throughput (the amount of light collected by the objective lens that actually reaches your eye or camera), when compared with standard coatings. They effectively add the equivalent of six-tenths of an inch of extra light-gathering aperture to the performance of the 8” scope with standard coatings, the equivalent of three-quarters of an inch of aperture to the 10” scope, and the equivalent of 0.85” of extra aperture to the 12” scope – but with no increase in size or weight. The UHTC multicoatings also improve contrast, for lunar and planetary images that appear sharper and more crisply defined.

• Fully baffled optics: A cylindrical baffle around the secondary mirror, in combination with the cylindrical baffle tube projecting from the primary mirror, prevents stray off-axis light from reaching the image plane. In addition, a series of field stops machined into the inner surface of the central baffle tube effectively eliminates undesirable light which might reflect from the inside surface of the baffle tube. The result of these baffle systems is improved contrast in lunar, planetary, and deep space observing alike.

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