The ETX is a line of telescopes

Optical telescope

An optical telescope is a telescope which is used to gather and focus light mainly from the visible part of the electromagnetic spectrum for directly viewing a magnified image for making a photograph, or collecting data through electronic image sensors....

 made by Meade Instruments.

Origins

The ETX started out as a line of Maksutov-Cassegrain

Maksutov telescope

The Maksutov is a catadioptric telescope design that combines a spherical mirror with a weakly negative meniscus lens in a design that takes advantage of all the surfaces being nearly "spherically symmetrical". The negative lens is usually full diameter and placed at the entrance pupil of the...

 telescopes by Meade. Meade's original 90 mm (3-1/2") Maksutov Cassegrain telescope (first produced in 1996) took advantage of high volume mass production

Mass production

Mass production is the production of large amounts of standardized products, including and especially on assembly lines...

 and simplified optical and parts construction to open a new market for a cheap alternative to the very expensive Questar 3-1/2 Maksutov Cassegrain The ETX "line" has been expanded to 105 mm, and 125 mm Maksutov Cassegrains and achromatic

Achromatic lens

An achromatic lens or achromat is a lens that is designed to limit the effects of chromatic and spherical aberration. Achromatic lenses are corrected to bring two wavelengths into focus in the same plane....

 refracting telescope

Refracting telescope

A refracting or refractor telescope is a type of optical telescope that uses a lens as its objective to form an image . The refracting telescope design was originally used in spy glasses and astronomical telescopes but is also used for long focus camera lenses...

s in sizes of 60 mm and 70 mm, but these two models were later replaced by a 80 mm model. The line has come to take advantage of "goto

GoTo (telescopes)

In amateur astronomy, "GoTo" refers to a type of telescope mount and related software which can automatically point a telescope to astronomical objects that the user selects...

" telescope mount

Telescope mount

A telescope mount is a mechanical structure which supports a telescope. Telescope mounts are designed to support the mass of the telescope and allow for accurate pointing of the instrument...

 technology, making it very popular with amateur astronomers

Amateur astronomy

Amateur astronomy, also called backyard astronomy and stargazing, is a hobby whose participants enjoy watching the night sky , and the plethora of objects found in it, mainly with portable telescopes and binoculars...

.

Maksutov-Cassegrain

The original 1996 model, now referred to as the "RA" or "classic" model, had a clockwork mechanism to track movement of the earth with an equatorial wedge, but it cannot be retrofitted for computer control.

In January of 1999, Meade introduced the ETX-EC which included electronic control of both axis through a small hand-controller. An optional #497 Autostar package was offered and would replace the simple electric controls, turning the ETX-EC into a fully computerized "goto" telescope.

Not officially a new model but rather a package (which eventually became standard), the "AT" package included an ETX-EC telescope bundled with the #497 Autostar controller and a stronger "deluxe" tripod.

Meade's UHTC (Ultra High Transmission Coating) treatment was first offered as an option on "EC" model telescopes (part of the "AT" bundle) in 2002. This coating improves light transmission by about 15%.

In October 2004, Meade announced the new ETX-PE or Premier Edition. The small right-angle finder scope was replaced on these models by an electronic module which included a level sensor, a magnetic north sensor, a real-time clock and a red-dot viewfinder. Also bundled was the PC interface cable. UHTC was still offered as an option. Early Premier Edition telescope had an image of the North American (ETX125) or Orion (ETX90) Nebulae printed on the optical tube.

Further revisions of the ETX-PE used a newer model Level-North module and Autostar controller (#497eq), made the UHTC coatings standard and went back to blue optical tubes.

Retail price of the ETX telescope has been constantly going down since its original 1996 introduction while capabilities and included accessories have increased dramatically.

Achromatic Refractors

In 2000, Meade added small 60mm and 70mm achromatic refractors to its ETX line. They were mounted on a dual fork mount similar to the larger models and included computer controls in the form of the #494 autostar.

At the time of introduction, they were some of the least expensive "goto" telescopes on the market.

Both models were replaced later by a single 80mm F/5 model.

Schmidt-Cassegrain

In 2009, Meade introduced the ETX-LS, a 150mm (6in) F/10 Schmidt-Cassegrain or ACF telescope on a very different single-fork arm. The LS include the Autostar III controller with over 100,000 objects in its database. It has a built-in CCD imager (E.C.L.P.S.) and a mini SD card reader for astrophotography. It includes audio and video descriptions of several hundred targets

External links

• Meade corporation ETX website
• Mighty ETX Comprehensive fan site.
• Meade UHTC optics Explanation by Meade Corporation.