LX90-ACF 10" Advanced Coma-Free Go-to altazimuth

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AutoStar software
An AutoStar Suite Software CD-ROM is included as standard equipment with each LXD-75, LX90, and LX200 telescope. This software package integrates the telescope with a Windows-based PC or laptop computer for an enhanced range of performance features. It includes a planetarium program with a database of 19,000,000 stars and deep space objects for display on your computer screen. All of the best on-screen display and star chart-printing features of a standard planetarium program are included for stand-alone use when nights are cloudy, or for planning observing sessions.

The software lets you enable or disable the Hubble Guide Star Catalog; set the on-screen Viewpoint to go to the current zenith or any R.A. and Dec. coordinate; choose any object by catalog name or number; enable or disable custom catalogs; add new catalogs; set magnitude limits; flip the star map for correct orientation as you observe through the telescope; zoom the star map display from 180° down to tiny fractions of an arc second; adjust label fonts and colors, coordinate grid colors, and brightness and contrast; enable or disable the night vision mode; and more.

In addition, if you connect the scope to your computer, the program lets you click on objects in the sky map that is displayed on the computer screen and have your telescope automatically slew to those objects. You can automatically generate AutoStar Tours of favorite objects with a simple point and click, as well as using the program to keep observing logs.

The software lets you control all AutoStar functions from your computer or laptop. You can use it to create observing lists and download them to the AutoStar for use in the field when you don’t have your computer or laptop with you. “Talking Telescope” software (included) converts AutoStar text displays to synthesized speech through your computer’s speaker. An AutoStar Update Tool in the software keeps your AutoStar II computer hand control current by downloading the latest system firmware updates and comet, asteroid, and satellite data from the internet.

You can also use the software to control your telescope remotely via the internet. Designed to be the ultimate platform for remote digital astronomy with your Meade telescope, the AutoStar Suite Astronomer’s Edition contains tools for dome controls, weather sensors, and other functions required for this purpose. You can reach your telescope and dome through a single network connection. You can then communicate via an IP address, using the AutoStar Net Scope program to control the entire observatory over the Internet. This solves the biggest problem in setting up for remote access to your telescope – the problem of your distance from the scope itself. You can be in your living room to control the scope in your backyard, or just as easily, control a friend’s system in another country!

The minimum computer requirements for installing the AutoStar Suite Software are a PC running Windows 98SE or later, with a minimum of 64 MB of RAM, and 200 MB of free hard disk space.

LX90 GPS computer
The built-in Sony GPS (Global Positioning Satellite) receiver and the AutoAlign software in the built-in AutoStar computer make aligning on the sky almost as easy as simply turning on your telescope. Take your LX90 outside and set it up on its supplied tripod. Turn it on. The LX90’s GPS receiver uses the radio signals from Earth-orbiting satellites to determine the telescope’s location on Earth with an accuracy measured in meters. From this information about where and when on Earth the telescope is located, the AutoAlign software determines what the sky looks like overhead and moves the telescope automatically to its first alignment star.
    If the star is not precisely centered in the crosshairs of the supplied 8 x 50mm finderscope, you use the AutoStar hand control pushbuttons to center it to improve the pointing accuracy. Let the scope repeat the process for its second alignment star and you’re ready to start observing. The GPS/AutoAlign system makes aligning your LX90 and finding your way around the night sky exceptionally easy, even for the first-time telescope owner.

The LX90’s AutoStar computer hand control plugs into the telescope’s fork arm to permit a wide array of telescope options. First and foremost is its automatic go-to capability. The AutoStar computer can show you the planets and thousands of deep space objects the very first night you use your scope – even if you've never used a telescope before! At the push of a button, the LX90 will move at a fast 6.5° per second to any of the 30,223 objects in its database. You can choose from 13,235 deep-sky objects from the complete Messier, Caldwell, IC, and NGC catalogs (sorted by name and type). Also included are 16,888 stars sorted by name, SAO catalog number, and by whether they are double or variable stars.
    The AutoStar will also locate the centroids of all 88 constellations and 50 objects in the solar system (8 major planets from Mercury to Pluto; the Moon; 26 asteroids; and 15 periodic comets). You can use it to track 50 Earth satellites, including the International Space Station, the Hubble space telescope, and Mir, plus any of 200 user-defined objects. You can also automatically move to any object that’s not in the database simply by entering its right ascension and declination coordinates. The AutoStar moves the LX90 at any of nine user-selectable slewing and guiding speeds: 6.5°/sec, 3°/sec, and 1.5°/sec for slewing and centering; as well as 128x, 64x, 16x, 8x, and 2x the sidereal rate for centering and astrophotographic guiding. In addition, there are standard lunar and sidereal tracking rates, plus a user-defined drive rate for precision tracking of the Sun and planets. The AutoStar includes a Smart Drive dual-axis drive corrector for long-exposure guided astrophotography (when used with an equatorial wedge in the polar mode). The Smart Drive has permanent periodic error correction that can be trained for finer and finer drive accuracy. You can even connect an optional #909 accessory port module to the rear cell of the LX90 to allow completely automatic CCD autoguiding of long exposure photos. The #909 also allows the use of an optional electric focuser and illuminated reticle eyepiece.
    The AutoStar computer includes hundreds of special event menus, guided tours, a glossary, utility functions, and telescope status options. It also allows fast alignment of the telescope in either an equatorial or altazimuth mode using any of three alignment methods, including Meade’s proprietary Easy Align method.
    The altazimuth drive of the LX90 is more than accurate enough for piggyback, lunar, and planetary 35mm photos and much CCD imaging. However, field rotation causes stars at the corners of an image to streak during exposures longer than five minutes if you don’t use an equatorial wedge to align the scope on the celestial pole. So, if you plan on doing long exposure deep space photography, you'll need to add the optional #2590 LX90 equatorial wedge to your 8” scope, and the #2570 Ultrawedge to your 10” or 12” scope.

LX90 GPS mount
The mount’s drive base is made of die-cast aluminum. The light-weight, but rigid, die-cast aluminum dual fork arms are shaped to damp vibrations quickly. There is a carrying handle on each fork arm. Both manual and electric slow motion controls are provided for both right ascension and declination. In addition to the digital readout of the scope’s aiming point in right ascension and declination on the AutoStar computer hand control, there are analog setting circles on the mount (5” in declination and 8.75” in right ascension). The drive base has a 4-port control panel, including two RS-232 serial interface ports for communication with an external computer and other ancillary equipment.

A 16-channel Sony GPS (Global Positioning System) receiver is built into the top of one of the fork arms. When the scope is turned on, the GPS receiver locks onto the network of orbiting GPS satellites to determine your observing location’s latitude, longitude, date, and time. It uses this information to tell the scope’s AutoStar computer where and when on earth the scope is located. Once the computer has this information, it orients the scope to the sky and slews at 6.5 degrees per second to the first of two alignment stars. If that star is not precisely centered in the finderscope or main scope optics, a touch or two on the Autostar hand control’s directional push buttons quickly centers it. Do the same with the second alignment star the scope moves to and the scope is then accurately aligned on the sky and ready to locate and track any celestial object you choose.

The mount includes servo-controlled 12VDC slewing and tracking motors with 4.9” worm gear drives in both altitude and azimuth. The drive system has individually selectable drive speeds in both right ascension and declination – 6.5°/sec, 3°/sec, and 1.5°/sec for slewing and centering; as well as 128x, 64x, 16x, 8x, and 2x the sidereal rate for centering and astrophotographic guiding. In addition, there are standard solar, lunar, and sidereal tracking rates with 2000 precision-selected incremental rates that permit observatory-level precision in tracking the Moon and planets.

The scope is powered by eight user-supplied C-cell batteries that store in the drive base so you can use the LX90 in the field or your backyard without the need for a separate battery pack or AC power supply. The usable life of the batteries is up to 60 hours, depending on the ambient temperature (colder temperatures reduce usable battery life). An optional #RCXAC adapter is available to allow you to power the scope from 110-120volt 60Hz AC household current in your backyard to conserve battery life. An optional #607 cigarette lighter plug cable is available to power the scope from your car's cigarette lighter plug or from a rechargeable battery for extended use in the field.

LX90-ACF UHTC optics
Features of this Telescope’s Optical System . . .
  • Advanced Coma-Free catadioptric designed to emulate the optical performance of a Ritchey-Chrétien telescope: The traditional two-mirror Ritchey-Chrétien (RC) design uses approximately hyperbolic primary and secondary mirrors to produce images that are free from coma over a wide field. Because of this wide coma-free field and a relatively fast focal ratio, the Ritchey-Chrétien design is particularly well suited to astrophotography. The RC is the design of choice for most of the major professional observatory telescopes built in the last half-century. For example, the Hubble Space Telescope and the twin 10-meter Keck telescopes in Hawaii are Ritchey-Chrétiens.
        However, because of the complexity of fabricating and testing a large aperture hyperbolic mirror (just ask the people who built the initially-flawed, but not discovered until it was in space, Hubble Space Telescope), traditional two-mirror Ritchey-Chrétiens are very expensive to manufacture and purchase, too expensive for many amateur astronomers.
        To emulate the coma-free performance of a true RC telescope, while keeping the cost very much within reason, the LX90-ACF Advanced Coma-Free (ACF) catadioptric optical system uses a full aperture aspheric corrector lens in conjunction with a simple spherical primary mirror. This creates a two-element primary mirror system that performs like an RC’s single hyperbolic primary mirror from the optical point of view of the LX90-ACF secondary mirror. The hyperbolic secondary mirror itself is mounted directly on the rear of the corrector lens, rather than in the traditional RC’s conventional spider vane assembly. This eliminates the image-degrading diffraction spikes of the secondary mirror support structure visible in commercial RC scope images. The result is RC-class coma-free wide-field performance in the LX90-ACF, at about a fifth the cost of most true RC systems.
        The corrector-modified design would itself be expensive to fabricate were it not for Meade’s more than a quarter-century of experience making Schmidt-Cassegrain correctors, which are in the same optical family as the corrector needed for the coma-free design of the LX90-ACF. An additional benefit of the full aperture corrector in the ACF design is slightly better correction for astigmatism than the traditional RC design.
        In addition, the LX90-ACF, due to its front corrector plate, is a closed tube design. This keeps the primary optical components protected from dust, moisture and other contaminants that might fall on the optical surfaces of the primary and secondary mirrors as can happen with the traditional open-tube RC design.
        While the LX90-ACF may not be a traditional RC design, its performance is RC-like in all important characteristics. A review in Sky & Telescope magazine of the ground-breaking predecessor of the Meade ACF optics said the bottom line is that the optics do “indeed perform like a Ritchey-Chrétien.” Another such review, in Astronomy magazine said, “This scope delivers Ritchey-Chrétien-like performance at a fraction of the cost.”

  • Oversized primary mirror: The diameter of the primary mirror of each LX90-ACF is larger than the diameter of the 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” is 12.375” in diameter. Oversizing the primary mirror in this way gives you a wider fully-illuminated field than a conventional catadioptric scope 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 model.

  • Fully multicoated UHTC (Ultra High Transmission Coatings) optics: The primary and secondary mirrors are vacuum-coated with aluminum, enhanced with multiple layers of titanium dioxide and silicon dioxide for increased reflectivity. A overcoating layer of durable silicon monoxide (quartz) assures long life.
        A series of anti-reflective coatings of aluminum oxide, titanium dioxide, and magnesium fluoride are vacuum-deposited on both sides of the full aperture 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 focal plane.
        UHTC multicoatings provide a 15% increase in light throughput compared with standard single-layer coatings. They effectively add the equivalent of 15% extra light-gathering area to the performance of a scope with standard coatings. It’s the equivalent of three-quarters of an inch of extra aperture in the case of a 10” scope, for example, but with no increase in actual size or weight. UHTC coatings 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 center of 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 tube. The result of these baffle systems is improved contrast in lunar, planetary, and deep space observing alike.
The Meade 10” LX90-ACF catadioptric telescope has Advanced Coma-Free optics to bring the astronomical image quality of a professional observatory to your back yard, at a down-to-earth price. It has a flat, coma-free field similar to that of the Ritchey-Chrétien reflector optics used in most professional observatory telescopes and the Hubble Space Telescope, but at a fraction the cost of a true Ritchey-Chrétien of similar aperture.
You don't have to know Polaris from the Pleiades, or Albireo from Zubeneschamali to align this big 10” LX90-ACF with Advanced Coma-Free UHTC multicoated optics on the skies for an evening of observing. Its standard equipment includes a GPS (Global Positioning Satellite) receiver and AutoAlign software in its AudioStar™ computer that makes the scope amazingly simple to set up and operate. Once set up, the Astronomer Inside™ its AudioStar™ computer hand control will talk to you, giving you four hours of audio descriptions of the celestial objects you are looking at and putting the knowledge and experience of a professional astronomer in the palm of your hand.
If you have the dark skies to take full advantage of its considerable light gathering (57% more than an 8” telescope), this scope can keep you happily observing and photographing for the rest of your life. Its UHTC multicoated optics are also 15% brighter than a 10” scope with conventional optical coatings, making deep space observing a joy. And it’s portable enough to make taking it to a dark sky site a reasonable proposition, even for one person.

This Telescope’s Optical System . . .
  • Advanced Coma-Free catadioptric designed to emulate the optical performance of a Ritchey-Chrétien telescope: 10” aperture (2500mm focal length f/10). Fully-multicoated UHTC (Ultra High Transmission Coatings) group optics with oversized primary mirror for the highest possible off-axis image brightness. Aluminum tube construction with glare-stop baffling. Guaranteed diffraction-limited performance. For more details, click on the “optics” icon above.

  • Finderscope:
  • Star diagonal: 1.25” 90° multicoated prism type.

  • Eyepiece: 1.25” 26mm Series 5000 Plössl (96x). The eyepiece field of view is 0.62°, 25% wider than the full Moon, for expansive lunar and deep space views that fill the eyepiece.

This Telescope’s Mount . . .

  • Fork mount/drive system: Die-cast aluminum drive base. Light-weight, but rigid, die-cast aluminum dual fork arms damp vibrations quickly. There is a carrying handle on each fork arm. The mount includes servo-controlled 12V DC slewing and tracking motors in both altitude and azimuth. The motors are powered by eight user-supplied C-cell batteries that fit into the drive base. The usable life of the batteries is up to 60 hours, depending on the ambient temperature.
    An optional #RCXAC adapter is available to power the scope from 110-120 volt 60 Hz AC household current in your back yard to conserve battery life. An optional #607 DC cord with a cigarette lighter plug is available to power the scope from your car’s cigarette lighter plug or a rechargeable battery for extended use in the field. For more details, click on the “mount” icon above.

  • Adjustable height tripod: The tripod is the same as the one used on Meade’s higher priced 8” and 10” LX200 scopes. Its 2” diameter steel legs adjust the tripod height from 30” to 44”. A single threaded rod with a large hand-tighten knob simultaneously holds the scope firmly on the tripod and locks the legs rigidly in the most stable position.

  • AudioStar™ computer: The AudioStar™ computer can show you the planets and thousands of deep space objects the very first night you use your scope – even if you've never used a telescope before! And a speaker built into the computer hand control lets the unique Astronomer Inside™ software provide you with more than four hours of fascinating audio descriptions of the objects you are observing. Astronomer Inside™ puts the experience and astronomical knowledge of a professional astronomer in the palm of your hand.
    At the push of a button, the LX90-ACF will move at a fast 6.5° per second to any of the 30,223 objects in its database. You can choose from Messier, Caldwell, IC, and NGC deep space objects, binary and multiple star systems, the Moon, planets, asteroids, and comets. You can also automatically move to any object that’s not in the database simply by entering its right ascension and declination coordinates. The AudioStar™ includes a dual-axis drive corrector with PEC (Periodic Error Correction). This allows long-exposure guided 35mm or large format CCD astrophotography in a polar mode, using an optional LX90 wedge #2590.) CCD imaging with one of the optional Meade Deep Sky Imagers with NASA-developed “Drizzle” software does not require an equatorial wedge. If you plan on doing a lot of deep space astrophotography, the 15% higher light transmission of this scope’s multicoated UHTC optics will allow shorter photographic exposure times, making deep space imaging easier.
    The AudioStar™ computer includes hundreds of special event menus, guided tours, a glossary, utility functions, and telescope status options. It also allows fast alignment of the telescope in either an equatorial or altazimuth mode, using any of three alignment methods, including Meade’s proprietary Easy Align method. For more details, click on the “computer” icon above.

  • AutoStar Software Suite: This software package is included as standard equipment with the LX90-ACF. It integrates the telescope with your PC or laptop computer for an enhanced range of performance features. It includes a planetarium program with a database of 19,000,000 stars and deep space objects to display on your computer screen. Connect the scope to your computer using the supplied cable, click on any object in the sky map on your computer screen, and your LX90-ACF automatically slew to that object. You can use it to control your telescope remotely via the Internet. “Talking Telescope” software (included) converts AutoStar text displays to synthesized speech through your computer speaker. And you can use all of the program’s planetarium features for planning future observing sessions when nights are cloudy by automatically generating AutoStar Tours of favorite objects with a simple point and click. For more details, click on the “AutoStar software” icon above.

    The simple tripod/altazimuth mount configuration of the 10” LX90-ACF with Advanced Coma-Free UHTC optics makes setup fast and easy. The GPS receiver, AudioStar™ computer, and its simplified Easy Align menus will start you observing in only a matter of minutes. The wide array of objects in the LX90-ACF database, and the 5 arc minute pointing accuracy of the AudioStar™ computer, will accurately speed you from object to object with no frustrating hunting or star hopping. With the LX90-ACF, you’ll spend more of your time looking at objects and less time looking for them. With the 15% additional light transmission of its UHTC optics you’ll spend less time photographing them, as well.
If you’re one of those busy people whose schedule doesn’t leave you much time to enjoy astronomy, an easy-to-use fully-computerized LX90-ACF with its unique Astronomer Inside™ software and talking AudioStar™ computer hand control will make the most of your limited observing opportunities.

What can you see through an 10” LX90-ACF with Advanced Coma-Free optics?

    With 57% more light gathering capability than an 8” telescope, this scope’s 10” catadioptric optics give the Universe a visual and photographic sharpness and grandeur at dark sky sites that no smaller telescope can approach – no matter how good that smaller scope might be.
The Orion Nebula shows an extension and subtlety of feature never visible through a smaller scope, particularly when you use a narrow band light pollution filter to increase the contrast of the fainter segments. Orion’s Trapezium stars A and C reveal their faint 11th magnitude visual binary companions. Nebular wisps and fragments such as the Veil show markedly greater extent than with any smaller scope. Faint galaxies and planetary nebulas, barely visible blurs in smaller scopes, start to reveal their structure in detail. Densely packed globular clusters are often resolved to the core. Thanks to the sharp coma-free field edge performance, all the stars in expansive open clusters stay sharply in focus across the full field, even in a very wide field eyepiece. Small storm cells in Jupiter's belts, plus tantalizing hints of surface details on its moons, can be seen under good seeing conditions, as can occasional dust storms on Mars. Cold and distant Pluto, a faint magnitude 13.9 speck, can be glimpsed making its lonely way across the skies.
With a photographic limiting magnitude of 17, all of these sights can be photographed in detail (with surprisingly short exposure times) by adding a few inexpensive accessories.
The altazimuth drive of the LX90-ACF is more than accurate enough for piggyback, lunar, and planetary 35mm photos and much CCD imaging. However, field rotation causes stars at the corners of an image to streak during exposures longer than five minutes if an equatorial wedge isn’t used to align the scope on the celestial pole. So, if you plan on doing deep space photography, you’ll need to add either an optional #2590 wedge or one of the optional Meade Deep Sky Imagers with NASA-developed “Drizzle” software that does not require an equatorial wedge.
This big 10” scope will perform adequately on faint deep space objects such as galaxies and nebulas under mildly light-polluted suburban skies, if provided with the proper light pollution filter. However, it is at a remote site with truly dark and steady skies that you’ll best be able to take full advantage of its large aperture, and superb flat field optical performance. This is not a scope that’s happy staying in a light-polluted city or suburban observing environment. But, if you have regular access to dark skies, and the size and weight of the scope (a 50 lb. optical tube to lift up onto the tripod) doesn’t daunt you, the 10” LX90-ACF with Advanced Coma-Free UHTC optics may be the perfect scope for you, particularly if you’re a deep space enthusiast.
If you’re one of those busy people whose schedule doesn’t leave you much time to enjoy astronomy, this easy-to-use fully-computerized LX90-ACF will make the most of your limited observing opportunities. It has all the aperture you need to keep you busy observing for the rest of your life, with enough useful features to handle almost any observing and astrophotography chore you set for it . . . and a price that won’t break the bank.
Just how much can you find to see and photograph with a 10” Meade LX90-ACF with Advanced Coma-Free UHTC optics? Enough wonders to last a lifetime!

Supplied Eyepiece:
The eyepiece that is supplied with this telescope.
SP26
Highest Useful Magnification:
This is the highest visual power a telescope can achieve before the image becomes too dim for useful observing (generally at about 50x to 60x per inch of telescope aperture). However, this power is very often unreachable due to turbulence in our atmosphere that makes the image too blurry and unstable to see any detail.

On nights of less-than-perfect seeing, medium to low power planetary, binary star, and globular cluster observing (at 25x to 30x per inch of aperture or less) is usually more enjoyable than fruitlessly attempting to push a telescope's magnification to its theoretical limits. Very high powers are generally best reserved for planetary observations and binary star splitting.

Small aperture telescopes can usually use more power per inch of aperture on any given night than larger telescopes, as they look through a smaller column of air and see less of the turbulence in our atmosphere. While some observers use up to 100x per inch of refractor aperture on Mars and Jupiter, the actual number of minutes they spend observing at such powers is small in relation to the number of hours they spend waiting for the atmosphere to stabilize enough for them to use such very high powers.
500x
Visual Limiting Magnitude:
This is the magnitude (or brightness) of the faintest star that can be seen with a telescope. The larger the number, the fainter the star that can be seen. An approximate formula for determining the visual limiting magnitude of a telescope is 7.5 + 5 log aperture (in cm).

This is the formula that we use with all of the telescopes we carry, so that our published specs will be consistent from aperture to aperture, from manufacturer to manufacturer. Some telescope makers may use other unspecified methods to determine the limiting magnitude, so their published figures may differ from ours.

Keep in mind that this formula does not take into account light loss within the scope, seeing conditions, the observer’s age (visual performance decreases as we get older), the telescope’s age (the reflectivity of telescope mirrors decreases as they get older), etc. The limiting magnitudes specified by manufacturers for their telescopes assume very dark skies, trained observers, and excellent atmospheric transparency – and are therefore rarely obtainable under average observing conditions. The photographic limiting magnitude is always greater than the visual (typically by two magnitudes).

14.5
Focal Length:
This is the length of the effective optical path of a telescopeor eyepiece (the distance from the main mirror or lens where the lightis gathered to the point where the prime focus image is formed). Focallength is typically expressed in millimeters.

The longer the focallength, the higher the magnification and the narrower the field of viewwith any given eyepiece. The shorter the focal length, the lower themagnification and the wider the field of view with the same eyepiece.

2500mm
Focal Ratio:
This is the ‘speed’ of a telescope’s optics, found by dividing the focal length by the aperture. The smaller the f/number, the lower the magnification, the wider the field, and the brighter the image with any given eyepiece or camera.

Fast f/4 to f/5 focal ratios are generally best for lower power wide field observing and deep space photography. Slow f/11 to f/15 focal ratios are usually better suited to higher power lunar, planetary, and binary star observing and high power photography. Medium f/6 to f/10 focal ratios work well with either.

An f/5 system can photograph a nebula or other faint extended deep space object in one-fourth the time of an f/10 system, but the image will be only one-half as large. Point sources, such as stars, are recorded based on the aperture, however, rather than the focal ratio – so that the larger the aperture, the fainter the star you can see or photograph, no matter what the focal ratio.

f/10
Resolution:
This is the ability of a telescope to separate closely-spaced binary stars into two distinct objects, measured in seconds of arc. One arc second equals 1/3600th of a degree and is about the width of a 25-cent coin at a distance of three miles! In essence, resolution is a measure of how much detail a telescope can reveal. The resolution values on our website are derived using the Dawes’ limit formula.

Dawes’ limit only applies to point sources of light (stars). Smaller separations can be resolved in extended objects, such as the planets. For example, Cassini’s Division in the rings of Saturn (0.5 arc seconds across), was discovered using a 2.5” telescope – which has a Dawes’ limit of 1.8 arc seconds!

The ability of a telescope to resolve to Dawes’ limit is usually much more affected by seeing conditions, by the difference in brightness between the binary star components, and by the observer’s visual acuity, than it is by the optical quality of the telescope.

0.46 arc seconds
Aperture:
This is the diameter of the light-gathering main mirror or objective lens of a telescope. In general, the larger the aperture, the better the resolution and the fainter the objects you can see.
10"
Weight:
The weight of this product.
70 lbs.
Heaviest Single Component:
The weight of the heaviest component in this package.
50 lbs.
Telescope Type:
The optical design of a telescope.  Telescope type is classified by three primary optical designs (refractor, reflector, or catadioptric), by sub-designs of these types, or by the task they perform.
Advanced Coma-Free
 
Based on Astronomy magazine’s telescope "report cards", scopes of this size and type generally perform as follows . . .
Terrestrial Observation:
Observing terrestrial objects (nature studies, birding, etc.) is usually possible only with refractor and catadioptric telescopes, and convenient only when the scope is on an altazimuth mount or photo tripod. Most reflectors cannot be used for terrestrial observing. Scopes with apertures under 5" to 6" are generally most useful for terrestrial observing due to atmospheric conditions (heat waves and mirage, dust, haze, etc.) that degrade the image quality in larger scopes. 
No
Lunar Observation:
Visual observation of the Moon is possible with any telescope. Larger aperture scopes will provide more detail than smaller scopes, thereby getting a higher score in this category, but may require an eyepiece filter to cut down the greater glare from the Moon's sunlit surface so small details can be seen more easily. Lunar observing is more rewarding when the Moon is waxing or waning as the changing sun angle casts constantly varying shadows to reveal craters and surface features by the hundreds.  
Very Good
Planetary Observation:
Very Good
Binary and Star Cluster Observation:
Very Good
Galaxy and Nebula Observation:
Very Good
Photography:
Yes
Terrestrial Photography:
Photographing terrestrial objects (wildlife, scenery, etc.) is usually possible only with refractor and catadioptric telescopes, and convenient only when the scope is on an altazimuth mount or photo tripod. Most reflectors cannot be used for terrestrial photography. Scopes with focal ratios of f/10 and faster and apertures under 5" to 6" are generally the most useful for terrestrial photography due to atmospheric conditions (heat waves and mirage, dust, haze, etc.) that degrade the image quality in larger scopes.
No
Lunar Photography:
Photography of the Moon is possible with virtually any telescope, using a 35mm camera, DSLR, or CCD-based webcam (planetary imager). While an equatorial mount with a motor drive is not strictly essential, as the exposure times will be very short, such a mount would be helpful to improve image sharpness, particularly with webcam-type cameras that take a series of exposures over time and stack them together. Reflectors may require a Barlow lens to let the camera reach focus. 
Yes
Planetary Photography:
Yes
Star Cluster / Nebula / Galaxy Photography:
Yes
Warranty:
1 year
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General Accessories
Books, Software, and Star Charts (2)
Stars And Galaxies, closeout
by Astro Media
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$29.95
$9.95 On Sale 
Galaxies And the Universe, closeout
by Astro Media
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Drive Motors and Drive Accessories (3)
Power Tank 7 Amp-hour 12V DC rechargeable battery
by Celestron
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$69.95 
Meade #607 Car Battery Cord
by Meade
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$24.95 
AC Power adapter for Meade LX200, LX90, ETX-90/105/125, LXD-75, and RCX400 scopes
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Extended Service Program (2)
Three-Year Sky Assurance™ For Meade telescopes priced between $2000 and $2999.99
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Five-Year Sky Assurance™ For Meade telescopes priced between $2000 and $2999.99
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Telescope Carrying Cases (1)
Hard case for Meade 10" LX200/LX200R and 10" LX50
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Visual Accessories
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Star Diagonals (1)
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  • 10” f/10 Advanced Coma-Free catadioptric optical tube assembly with UHTC optics (multicoated aluminum mirrors and a multicoated Schmidt corrector)
  • Double-tine fork mount with dual-axis 4.9” worm gears and control panel
  • Built-in Sony GPS receiver
  • Electric slow-motion controls on both axes
  • AudioStar hand controller with Astronomer Inside and digital readout display, 9-speed drive controls on both axes, and go-to controller
  • 30,223-object onboard celestial software library
  • Internal battery port accepts 8 (user-supplied) C-cells (optional 25 ft. cords permit powering from either 12vDC auto cigarette lighter plug or from 110-120VAC home outlet)
  • 8 x 50mm straight-through viewfinder
  • 1.25” diagonal prism
  • Series 4000 Super Plössl 26mm eyepiece (96x)
  • AutoStar Astronomer’s Edition Software Suite
  • Standard field tripod
  • Operating instructions.
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Meade - LX90-ACF 10" Advanced Coma-Free Go-to altazimuth

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Meade - LX90-ACF 10" Advanced Coma-Free Go-to altazimuthImage showing closer view of the two finderscopes.Image showing the telescope mounted on its full-length adjustable-height altazimuth field tripod.
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Our Product #: 10910ACF
Manufacturer Product #: 1010-90-03
Price: $2,649.00  FREE ground shipping - Click for more info
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Clear skies,
Astronomics


If you have the dark skies to take full advantage of the immense light gathering capacity of this Meade 10” LX90-ACF with Advanced Coma-Free UHTC multicoated optics, this scope can make you a happy astronomer for the rest of your life. The price of this big (but still one-person portable) and very full-featured telescope won’t empty your bank account, either . . .





. . . our 34th year