Last modified: October 28, 2004
Our ETX-90 Telescope
This is a description of our telescope, an ETX-90 instrument made by Meade Instruments Corporation, with the optional Ultra-High Transmission coatings (UHTC).
ETX-90 UHTC Specifications
| Manufacturer Number | 030922 |
| Product Number | 3514-03-21 w/o 0309004-M |
| Optical design | Maksutov-Cassegrain |
| Primary mirror diameter | 96mm (3.78") |
| Clear aperture | 90mm (3.5") |
| Focal length | 1250mm |
| Focal ratio (photographic speed) | f/13.8 |
| Near focus (approx.) | 3.5m (11.5') |
| Resolving power | 1.3 arc secs |
| Limiting visual stellar mag (approx.) | 11.7 |
| Image scale | 1.16 deg/inch |
| Maximum practical visual power | 325X |
| Materials and coatings | Grade-A BK7 optical glass corrector lens with multiple layers of Al203, Ti02, and MgF2 coatings on both sides; Pyrex primary mirror with aluminum/silicon monoxide coatings on both primary and secondary mirrors |
| Telescope dimensions | 15" x 7.3" x 8.5" |
| Telescope net weight | 4.2kg (9.2 lbs) |
| Optical tube dimensions (dia x length) | 10.4cm (4.1") x 27.9cm (11") |
| Secondary mirror obstruction (dia; %) | 27.9mm (1.1"); 9.6% |
| Telescope mounting | Double-tine fork |
| Motor drive system | 9-speed DC servo motors with encoders, both axes |
| Slo-motion controls | Electric, 4 speed, both axes |
Included Accessories:
- Meade #497 Autostar
- Meade #884 Deluxe Field Tripod
- Meade #07426 8x21mm Erect-Image Viewfinder (For ETX)
- Meade Series 4000 #07175-03 26mm-LP Super Plössl (1.25" O.D.)
Meade Super Plössl eyepiece set:
| Eyepiece focal length(mm) | Power | 2x Barlow |
|---|---|---|
| 6.4 | 195.31 | 390.63* |
| 9.7 | 128.87 | 257.73 |
| 12.4 | 100.81 | 201.61 |
| 15 | 83.33 | 166.67 |
| 20 | 62.50 | 125.00 |
| 26 | 48.08 | 96.15 |
| 32 | 39.06 | 78.13 |
| 40 | 31.25 | 62.50 |
* 325x is the maximum practical visual power for the ETX-90
