MSRP: $4,060.00 Sale Price: $2,479.00 Savings $1,581.00
Celestron C-11 A Telescope
Item No. 602-91067 Manuf. No. Celestron 91067-XLT
This 24" long aluminum optical tube weighs only 27.5 lbs., making it easy to transport. It has an 11" aperture, a 2800mm focal length, and a focal ratio of f/10. An optional focal reducer is available to bring the focal ratio down to f/6.3 for CCD and 35mm photography. Optical performance is guaranteed to be diffraction-limited.
Advanced high transmission Starbright XLT optical multicoatings are standard equipment. This coatings package includes high reflectivity multilayer aluminum mirrors enhanced with titanium dioxide for high reflectivity, plus a unique combination of magnesium fluoride and hafnium dioxide antireflection coatings on both sides of the Schmidt corrector lens. The corrector lens itself is made of high transmission water white float glass instead of conventional soda lime glass (which has 3.5% lower transmission) used in other telescopes.
Starbright XLT multicoatings visibly increase the contrast on subtle lunar, planetary, and nebula details when compared with a scope with standard multicoatings. They also 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 optics are hand-figured. 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 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. He then fabricates a precision pitch lap and delicately hand polishes the secondary mirror to compensate for any small residual zonal defects and smooth the optical figure. 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 hand-crafting well worth the effort.
The optical tube comes with a big 9 x 50mm straight-through achromatic finderscope and mounting bracket. The finder has a wide 5? field of view. It focuses by loosening the trim ring behind the objective lens cell, screwing the lens cell in or out to focus, and tightening the trim ring to lock in the correct focus. Also standard is a removable 1.25" visual back that holds visual accessories such as a star diagonal, tele-extender, etc. A 1.25" prism type star diagonal is also standard, as is a 1.25" 40mm Plossl eyepiece. This eyepiece provides a magnification of 70x. Its field of view is 0.68? across, over a third wider than the full moon. Dust covers for the optics are also supplied.
A 1.75" wide dovetail slide bar runs the length of the tube for mounting the optical tube on a Celestron CG-5 German equatorial mount or Advanced Series go-to mount, on the Meade LXD75 mount, or on a Vixen Great Polaris German equatorial mount or Sphinx go-to mount. Optional split mounting rings are also available to put the tube on any another mount of the buyer?s choosing.
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