Meade ETX-90 (2003)

90mm Maksutov-Cassegrain catadioptric

ETX 90

Fun scope, good optics, so-so drive (this is the original ETX)

It is remarkable what you can see with this little gem, but you need a lot of patience to master it. 
- Long focal length makes it challenging to locate objects. 
- Finder is very difficult to use.
- Controls are small and located close together. 
- Focus is very touchy - the slightest turn and you blow right through focus.
- Lots of vibration when the scope is touched, works a little better on a heavy tripod.

Optical tube is aluminum and has a threaded aluminum lens cap.

Power is provided by AA batteries inside the base, they last a long time.

 A JMI hard case provides excellent protection and has enough space to carry a few eyepieces, legs, batteries, flashlight, etc.  I take the scope camping a lot.  Doesn't take up a lot of room in the RV and with everything in the one case there is nothing else to remember.

Specs:

Primary 96mm - Pyrex
Clear Aperture 90mm - BK7 optical glass, Grade-A
Focal Length - Focal Ratio 1250mm - f/13.8
Coatings Super Multi-Coatings EMC - standard
Limiting Magnitude 11.7
Max Practical Magnification 325x
Secondary Mirror - Obstruction 27.9mm - 9.6%
Eyepieces * 9 & 25mm MA *
Weight 9.2 lbs
ETX Front
* Plossl eyepieces are standard equipment, but this scope is a Sam's Club item.

ETX Back

Back End

The size of this scope makes it a little difficult to use.  Everything is close to something else.  Real easy to get the wrong knob in the dark.

Center of the back is a port for camera use, the two knobs on either side of the port work a flip-mirror.

Above the right flip-mirror knob is the focus, to the right of that is the declination lock

   
ETX Finder

Finder

8x21 straight-through

Almost impossible to focus while mounted - remove it, focus it, realign it

Where it is located makes it very challenging to look through.  A popular upgrade is to replace it with a small right-angle finder.

   
ETX Right

Right side

A better view of the declination lock.  Focus is the small knob protruding out of the back of the scope.  The lower knob is the flip-mirror.

   
ETX RA

RA & Declination controls

Right knob is the declination control.  The declination adjustment is not continuous.  When it reaches the end of travel about 50 turns in the opposite direction is required to center the mechanism.

Center is the RA lock, left knob is the RA control.  Lock must be disengaged to use the RA knob.

   
ETX Altitude

Latitude adjustment

Three legs are provided to polar align the scope on a table top.  I usually use a tripod instead.

The leg is calibrated for use from 27.5 to 42.5.  Two additional holes are in the base for latitudes above and below this range, but the markings on the leg will be useless.

A handy site for a lot of ETX (all models) information: Weasner's Mighty ETX Site

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