Meade ETX-90 User manual

The Meade ETX Telescope

A Tutorial for both Basic and

Advanced Setup

A Service Provided by the

The Meade ETX 90

The Meade ETX series is a sophisticated entry level

telescope suitable for people that would like to view

the night sky without spending a huge amount of

money. They actually have many of the features found

in more of the higher priced & more advanced

telescopes available. The biggest difference is the size

of the Optical Tube Assembly (OTA) and its ability of

gather light from the darkness of the night sky.

Although this telescope is deemed as an entry level

scope it is still a precision instrument in its own right. It

comes with an instruction manual that can be very

frustrating to understand by a person just starting out.

Once there is an understanding of what the manual is

trying to convey, that knowledge is very useful to the

person that is of a mind to upgrade their telescope

system to a more powerful light gathering model

First Step

Make an honest attempt to read and understand the

manual and have the scope and its various parts on

hand while doing so. Don’t be in a rush to set the scope

up and expect to see “Hubble Space Telescope” images

after your first observation session. The ETX is a long

way away from the “Hubble”. The ETX is great for

viewing the moon and many of the various planets in

our solar system. Most of the “Deep Sky Objects” such

as Nebulas and distant Galaxies that might be nothing

more than a smudge in the night sky when viewed with

the naked eye, will be just a more defined smudge when

viewed through the ETX. Reading the manual at least

two to three times is a good idea.

Once becoming totally confused after reading the manual you will most likely just

want to set the scope up and get with the program so let’s do it.

The tripod should come with its

own duffle bag and it can be a

struggle to extract the tripod and

later put it back in.

The Instruction manual is actually pretty clear on how to

set the tripod up but there is one tip to keep in mind.

Don’t extend the legs all the way out, leave a little bit of

length for leveling adjustment later. With the legs fully

extended a person sometimes has to adjust two legs

whereas if there was some length left, adjusting one leg

would do the trick. Adjusting the height of the tripod is

an exercise in “trial & error” and the correct height will

only be settled on after several observation sessions and

each adjustment messes with the level of the scope.

While setting up your tripod, line up the Latitude

adjustment rod of tripod’s mounting plate to the

back and the forward leg to either “True North” or

”Magnetic” North. This will come in handy when

you have to align the telescope with a couple of

“alignment stars” later. Also get the top mounting

plate as level as possible by adjusting the length of

the tripod’s legs. A useful tool in performing these

operations is one’s cell phone using the compass

function and a free “level app”.

Another thing to note is that after mounting the telescope to the tripod as shown in the

instruction manual, it might be necessary to lift the entire telescope/tripod assembly in

order to get the telescope pointed in the direction of either “True North” or “Magnetic

North” after setting the scope to its “Home Position”. The operation of leveling the

scope might have to be repeated and the adjustments should be very minor.

(There is no real Front or Back on the Telescope but on the bottom of the Telescope base

there should three small rubber pads. Assemble the scope so the two pads are in the

back with the single pad facing forward. The control panel at the base of the scope

should be on the left side. Orienting the scope in this way will provide for full range of

motion when the telescope “Slews” to a selected target in the Night Sky. This is called the

default “Alt/Az” mount)

Mount the Telescope to the Tripod

The instruction manual shows in very good detail how to mount the scope to the tripod.

For the most part there is no reason to concern yourself with what the latitude control

arm and latch does. All you want to do is loosen the latch, raise the attached plate to

expose the knobs of the telescope attachment screws. Follow the directions to get the

scope securely fastened to the tripod mounting plate. Push the plate down all the way

and tighten the latch. At this point, take the dust cover off the eye piece holder and

replace it with an eye piece. Tighten the set screw to secure the eye piece in the holder.

Aligning the Finder Scope with the Optical Tube

This is an important step. Getting this done right will greatly increase one’s chances for

success when trying to locate something in the night sky. All of the next several set up

operations should be done outside in the daylight hours. Pick something out in the

distance no closer than 200 yards, preferably farther. Remove the dust cover from the

front of the optical tube, loosen the horizontal latch at the base of the scope while

loosening the vertical knob on the right fork of the scope. Loosen these to the point

where scope can be easily turned side to side & up and down with a small amount of

resistance.

Finder Scope Optical Tube Alignment (continued)

Some models of the ETX, depending on date of

manufacture, have different Finder Scopes. Some

have an electronic red dot and others might have a

low power scope with crosshairs, mounted to the

main telescope body.

Use the Finder Scope to aim the main Optical Tube at the intended target in the distance

and then look through the Telescope Eye Piece. Most likely you are going to have to turn

the focus knob on the scope in order to see anything at all. Also, when viewing through

the eye piece, the image is backwards, so up is down, down is up, right is left and left is

right. Make whatever adjustments are necessary to get the intended target in the viewing

center of the Eye Piece. Take your time, this backwards way of looking at things is the

same in most if not all telescopes available to the backyard astronomer. This image can be

“corrected” if a person wants to spend some money and if something might actually be

available to do so, just get use to it.

Once the target is centered in the main telescope, lock down both the horizontal and

vertical adjustments. Now adjust the Finder Scope so its center of target matches that of

the main Telescope. Now both the main scope and spotting scope should be aligned. In

the future, the Finder Scope, with its wider field of view will greatly assist in the search

and finding the selected targeted objects for night sky viewing.

Put the Telescope into its Home

Position

With the alignment of the spotting scope

and main Optical Tube complete, get the

scope set up in its “Home Position” for the

operation of “Training the Drive.”

Loosen the “horizontal” lever at the base

of the scope and turn the scope counter

clockwise until it comes to a stop. Now

turn the scope clockwise until one of the

fork mounts lines up with the power

controls on the scope base. Lock down the

horizontal lever. Replace the eye piece

with the combination bubble

level/compass that is included is the

telescope package. If that is missing, put

your cell phone on top of the eye piece

holder and use the compass and level

apps. If necessary lift the entire assembly

to achieve “True or Magnetic North”

alignment of the optical tube.

Loosen the vertical lock knob on the right

fork of the telescope to adjust the optical

tube with the use of the bubble level or cell

phone app. You might have to adjust the

tripod legs in order to center the bubble in

the level. With some practice, this

operation becomes much easier.

Training the Drive

It is assumed that batteries have been installed into the telescope or that the scope is being

supplied with power from some source. If that is not the case, disassemble the scope from

the tripod and install the batteries. After reassembly, don’t worry about any alignment

issues with the spotting scope, that is taken care of. The scope should still be pretty level,

just do a quick check to confirm and move on.

In the back of the Instruction Manual is a section called “Training the Drive.” You are are

going to power up the scope and use the “AudioStar Handset.” (The Instruction Manual

might refer to the Handset as the “AutoStar Handset.” It is “Audio” because when you select

an object a voice from the Handset will describe the object in detail.) Read the directions

first before doing anything. Sometimes there is a thing where the “cart gets before the

horse.” If you read the directions first there is less of a chance of that happening.

What Training the Drive does is help with aiming issues so the scope returns accurately from

one celestial object to another. The AudioStar Handset is a small computer that controls all

the scope’s movements. Pick something displayed on the handset menu, press the “GoTo”

button and the scope moves to point directly to that object. A step in getting the scope to

move and accurately settle in on the desired object is to “calibrate” it so all the movements

are repeatable. That is what “Training the Drive” does. This only has to be done very

infrequently or if there is a decided lack of accuracy in where the scope is pointing.

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