|
Click here for recommended accessories |
|
|
Premium Meade® LXD75 Optics
Diffraction-Limited Optics
Meade's Schmidt-Newtonian and Schmidt-Cassegrain optics yield pinpoint stellar images over an extremely wide field-of-view with
only half the coma of standard Newtonians of the same focal ratio.
Optical Tube Construction
Schmidt-Newtonian and Schmidt-Cassegrain optics are mounted in precision-machined aluminum cells, which are then mounted in
sturdy steel tubes that are baked with high-grade textured enamel paint. The optical tube assembly is closed, reducing air
currents inside the tube. This prevents distortion of an otherwise sharp image. Plus, a closed tube significantly helps keep the
optics clean.
Corrector Lens
Fully corrects for spherical aberration and provides pinpoint star images. Water-white glass is used in all Schmidt-Newtonian and
Schmidt-Cassegrain corrector lenses to maximize light transmission. The use of water -white glass increases light transmission by
more than 10%, as compared to competitive telescopes using soda-lime glass.
Individually Figured Optics
Schmidt-Newtonian and Schmidt-Cassegrain corrector lenses and mirrors are individually figured to create a superior optical
system that is renowned for its exquisite smoothness and performance.
Pyrex® Primary Mirror
Premium-grade Pyrex mirrors are used in all Schmidt -Newtonian and Schmidt-Cassegrain optical systems, providing exceptional
thermal stability versus competing models using standard plate glass.
System Highlights
* Sturdy Mount with Heavy-Duty Castings: Designed by Meade's engineers and manufactured for high-performance observing and
astrophotography.
* Shaft & Bearing System: The sturdy German Equatorial Mount is accurate and precise. The RA and Dec axes move effortlessly
on four high-precision stainless steel ball bearings.
* High-Precision Worm Gears: Located on both axes for smooth tracking and slewing.
* High-Precision Pointing (HPP): For even more-precise pointing, use the HPP function. HPP puts objects in the center of the
field-of-view, which allows you to confirm deep-sky objects at the faintest limits of the telescope's capability.
* Periodic Error Correction: Corrects periodic errors on the RA axis over the course of one or more training periods, thereby
minimizing guiding corrections during long-exposure photography.
* 9-Speed Drive Controls: From a rapid slew rate of 4.5°/sec. to 1x sidereal – it's all controlled from the Autostar
controller.
* 3-Star Alignment: Ensures precise alignment while eliminating the need for a complicated optical/mechanical alignment
process.
* Heavy-Duty Tripod: Variable-height field tripod with spreader bar brace provides the stability and vibration damping
required for visual observation and astrophotography.
* Illuminated Polar Alignment Viewfinder: For quick, precise polar alignment.
* Power Supply: Powered by 8 D-size batteries. Can also be powered by optional car cigarette lighter or AC wall adapter.
* Enhancements
New Optical Tube Assemblies
The LXD75 Schmidt-Newtonians are supplied with an upgraded 8x50 viewfinder, and the standard precision all-metal 1.25"/2" O.D .
rack & pinion focuser.
Stable Meade LXD75 German Equatorial Mount
Designed for high-performance observing and astrophotography, the LXD75 Series sets a new Meade standard in their price class for
sturdiness, precision operation and smoothness of movement. With the LXD75, Meade engineers have created a virtually backlash-free
equatorial mount incorporating heavy-duty castings and four high-precision stainless steel ball bearings in both RA and Dec axes.
New Design LXD75 Drive System
The reliable LXD75 drive system has enhanced precision alignment of the motor gear assembly for greatly reduced backlash and
tracking smoothness.
New Design Heavy-Duty Tripod
The new, heavy-duty, all-metal field tripod utilizes a locking spreader bar (with three 1.25" eyepiece holders) to lock each leg
in place, virtually eliminating flexure. Each leg has two anodized aluminum leg extension locks with an internal brake to
eliminate slipping of the internal extending leg. These locks are inward facing so that no accidental bumping of the leg locks can
occur.
Features:
* Autostar Suite
* Available with either: Standard or UHTC (Ultra-High Transmission Coatings Group)
* 2" Focuser: Aluminum rack and pinion focuser allows the user to achieve a precise focus.
* Eyepiece Holder: Accepts both 1.25" & 2" eyepieces. Allows use of all common telescope accessories and cameras.
* 8x50 Achromatic Viewfinder: Easily locate and center deep-sky objects.
* Made in the U.S.A. and Performance Tested: All Meade Schmidt-Newtonian and Schmidt -Cassegrain optics are manufactured at
Meade's state-of-the-art facility in Irvine, Calif., then performance tested on an Interferometer
|
An important optional feature to optimize the performance of your Meade telescope.
Image brightness in a telescope is crucially dependent on the reflectivity of the telescope's mirrors and on
the transmission of its lenses. Neither of these processes, mirror-reflectivity or lens-transmission, is,
however, perfect; light loss occurs in each instance where light is reflected or transmitted. Uncoated glass,
for example, reflects about 4% of the light impacting it; in the case of an uncoated lens 4% of the light is
lost at entrance to and at exit from the lens, for a total light loss of about 8%. |
Early reflecting telescopes of the 1700's and 1800's suffered greatly from mirrors of poor reflectivity- reflection losses of 50%
or more were not uncommon. Later, silvered mirrors improved reflectivity, but at high cost and with poor durability. Modern
optical coatings have succeeded in reducing mirror-reflection and lens-transmission losses to acceptable levels at reasonable
cost.
Meade Standard Coatings: The optical surfaces of all Meade telescopes include high-grade optical coatings fully consistent in
quality with the precision of the optical surfaces themselves. These standard-equipment coatings include mirror surfaces of highly
purified aluminum, vacuum-deposited at high temperature and overcoated with silicon monoxide (SiO), and correcting lenses coated
on both sides for high light transmission with magnesium fluoride (MgF2). Meade standard mirror and lens coatings equal or exceed
the reflectivity and transmission, respectively, of virtually any optical coatings currently offered in the commercial telescope
industry.
The Meade UHTC Group: Technologies recently developed at the Meade Irvine coatings facility, however, including installation of
some of the largest and most advanced vacuum coating instrumentation currently available, have permitted the vacuum-deposition of
a series of exotic optical coatings precisely tuned to optimize the visual, photographic, and CCD imaging performance of Meade
telescopes. These specialized, and extremely advantageous, coatings are offered here as the Meade Ultra-High Transmission Coatings
(UHTC) group, a coatings group available optionally on many Meade telescope models.
In Meade catadioptric, or mirror-lens, telescopes (including the ETX-90EC, ETX-105EC and ETX-125EC; LX10, LX90, and LX200GPS
Schmidt-Cassegrains; and LXD55-Series Schmidt-Newtonians) before incoming light is brought to a focus, it passes through, or is
reflected by, four optical surfaces: the front surface of the correcting lens, the rear surface of the correcting lens, the
primary mirror, and the secondary mirror. Each of these four surfaces results in some loss of light, with the level of loss being
dependent on the chemistry of each surface's optical coatings and on the wavelength of light. (Standard aluminum mirror coatings,
for example, typically have their highest reflectivity in the yellow region of the visual spectrum, at a wavelength of about
580nm.)
Mirror Coatings: Meade ETX, Schmidt-Cassegrain, and Schmidt-Newtonian telescopes equipped with the Ultra-High Transmission
Coatings group include primary and secondary mirrors coated with aluminum enhanced with a complex stack of multi-layer coatings of
titanium dioxide (TiO2) and silicon dioxide (SiO2). The thickness of each coating layer precisely controlled to within +/-1% of
optimal thickness. The result is a dramatic increase in mirror reflectivity across the entire visible spectrum; at the important
hydrogen-alpha wavelength of 656nm. - the predominant wavelength of emission nebulae - reflectivity is increased from 89% to over
97%.
Correcting Lens Coatings: Meade telescopes ordered with the UHTC group include, in addition, an exotic and tightly-controlled
series of coatings on both sides of the correcting lens or correcting plate, coatings which include multiple layers of aluminum
oxide (Al2O3), titanium dioxide (TiO2), and magnesium fluoride (MgF2). Per-surface light transmission of the correcting lens is
thereby increased at the yellow wavelength of 580nm., for example, to 99.8%, versus a per-surface transmission of 98.7% for the
standard coating.
The importance of the UHTC group becomes apparent when comparing total telescope light transmission, or throughput, caused by the
multiplier, or compounding, effect of the four optical surfaces. With each optical surface contributing significantly to telescope
light throughput, the effect of all four surfaces combined is indeed dramatic, as demonstrated by the graphs on the facing page,
as well as by the table of the brightest nebular emission lines. At the H-alpha wavelength of 656nm., total transmission increases
from 77% to 93%, an increase of 93/77 or 21% at all three nitrogen-III and sulfur-II wavelengths of 655nm. and 673nm.- prominent
lines in certain galactic nuclei and in supernova remnanats such as the Crab Nebula- transmission increases by 21%; ; at the
helium wavelengths of 588nm. and 469nm. - strong emission lines in hot planetary nebulae - total telescope transmission increases
by 18% and 19%, respectively; at the two nitrogen II lines of 655nm. and 658nm. and at the sulfur II line of 673nm., transmission
is increased by 21%. Averaged over the entire visible spectrum (450nm. to 700nm.), total light transmission to the telescope focus
increases by about 20%.
Observing with the UHTC: Meade ETX, Schmidt-Cassegrain, and Schmidt-Newtonian telescopes equipped with the UHTC present
dramatically enhanced detail on the full range of celestial objects - from emission and planetary nebulae such as M8, M20, and M57
to star clusters and galaxies such as M3, M13, and M101. Observations of the Moon and planets, since they are observed in
reflected (white) sunlight, benefit in image brightness from the full spectrum of increased transmission. The overall effect of
the UHTC is, as it relates to image brightness, to increase the telescope's effective aperture. Image brightness (i.e., the
ability to see faint detail) of the Meade 10" LX200GPS is, for example, effectively increased by about one full inch of aperture.
| Emission Line | Wavelength (nm.) | Transmission: Standard Coatings (%) | Transmission: UHTC Group
(%) | Increase* |
| Hydrogen-alpha (Ha) | 656 | 76.9 | 93.1 | 21% |
| Hydrogen-beta (Hb) | 486 | 75.3 | 85.8 | 14% |
| Oxygen III | 496 | 76.5 | 85.4 | 12% |
| Oxygen III | 501 | 77 | 85.4 | 11% |
| Helium II | 496 | 72.5 | 86.1 | 19% |
| Helium I | 588 | 79.5 | 93.5 | 18% |
| Nitrogen II | 655 | 77 | 93.2 | 21% |
| Nitrogen II | 658 | 76.7 | 92.8 | 21% |
| Sulfer II | 673 | 75.7 | 91.8 | 21% |
* The % increase is obtained by dividing the UHTC-transmission (column 4) by the standard coatings transmission
(column 3).
Effects on CCD Imaging: While the human eye loses sensitivity to light beyond wavelengths of about 700nm., CCD imaging chips
remain sensitive to about 750nm. and longer, wavelengths at which the reflectivity of an aluminum coating is near its lowpoint.
Importantly, however, the UHTC's total light transmission at 750nm. is 83%, vs. 72% for standard coatings, an increase of 83/72,
or 15%.
|
|
Sturdy Mount with Heavy-Duty Castings Designed by Meade's engineers and manufactured for high-performance observing and
astrophotography.
Shaft & Bearing System The sturdy German Equatorial Mount is accurate and precise. The RA and Dec axes move effortlessly
on four highprecision stainless steel ball bearings.
High-Precision Worm Gears Located on both axes for smooth tracking and slewing.
High-Precision Pointing (HPP) For even more precise pointing use the HPP function. HPP puts objects in the center of the
field-of view which allows you to confirm deep sky objects at the faintest limits of the telescope's capability.
Periodic Error Correction Corrects periodic errors on the RA axis over the course of one or more training periods, thereby
minimizing guiding corrections during long-exposure photography.
9-Speed Drive Controls From a rapid slew rate of 4.5°/sec. to 1x sidereal-it's all controlled from the AutoStar
controller. 3-Star Alignment Ensures precise alignment. It eliminates the need for a complicated optical/mechanical alignment
process.
Heavy-Duty Tripod Variable-height field tripod with spreader bar brace provides the stability and vibration damping
required for visual observation and astrophotography.
Illuminated Polar Alignment Viewfinder For quick, precise polar alignment.
Power Supply Powered by 8 D-size batteries. Can also be powered by optional car cigarette lighter or AC wall adapter.
MEADE AUTOSTAR® The AutoStar controller helps you quickly find, and GO TO over 30,000 objects in the night sky. View
planets, stars, galaxies, nebulae, and comets…all at the push of a button. AutoStar is pre-programmed with several guided tours,
including the popular Tonight's Best™. Input date, time and location-then let AutoStar take you on a guided tour of the best
objects that particular night.
STANDARD FEATURES
* Telescope Mounting: LXD75, German-type
* Setting Circle Diameters, RA and Dec.: 2.25"
* Polar Illuminated Viewfinder: included
* RA Control System: 9-speed, microprocessor-controlled, 12v DC, 72mm (2.83") worm gear
* Declination Control System: 9-speed, microprocessor-controlled, 12v DC, 72mm (2.83") worm gear
* Hemispheres of Operation: North and South
* GO TO Pointing Precision (approx.): 15 arc mins.
* Slow-Motion Controls: electric, both axes
* Bearings: 2 – Ball Bearings RA: outer – 1x58mm, 1x47mm; inner – 1x45mm, 1x35mm DEC: outer – 1x72mm, 1x47mm; inner – 1x55mm,
1x30mm
* AutoStar® Hand Controller: PIC 16C57 microcontroller; 2 line x 16 alphanumeric character display; 20-button keypad, red
LED backlit
* Main Telescope Controller: Motorola® 68HC11 microprocessor; 1-Megabyte flash memory (field reprogrammable); 32K RAM
* Batteries (user-supplied): 8 x D-cells. LXD75-Series models may alternatively be powered from an automobile cigarette
lighter plug, using the #607 Power Cord, or from a 115v AC home outlet, using the #547 AC Adapter; both the #607 and the #547
include 25 ft. cords. (not included)
* Battery Life (approx.): 40 hours
* Onboard Celestial Object Database: 30,223 objects
* Slew Speeds both axes: 1x, 2x, 8x, 16x, 64x, 128x sidereal; 1.5°/sec., 3°/sec., 4.5°/sec.
* Tracking Rates: sidereal, lunar, or custom-selected from 2000 incremental rates
|
