| TELESCOPE
Model |
ETX-90EC |
ETX-105EC |
ETX-125EX |
| |
|
Optical Design
|
Maksutov-Cassegrain |
Maksutov-Cassegrain |
Maksutov-Cassegrain |
| Primary
Mirror Diameter
|
96mm (3.78")
|
116mm (4.56")
|
138mm (5.43")
|
|
Clear Aperture
|
90mm (3.5") |
105mm (4.13") |
127mm (5.0") |
| Focal
Length, Focal Ratio
|
1250mm f/13.8
|
1250mm f/13.8
|
1900mm f/15
|
|
Near Focus
(approx.) |
11.5 ft. (3.5m) |
15 ft. (4.6m) |
15 ft. (4.6m) |
| Resolving
Power (arc secs.) |
1.3 |
1.1 |
0.9 |
|
Optical Coatings
|
MgF2; standard aluminum/SiO
|
MgF2; standard aluminum/SiO
|
MgF2; standard aluminum/SiO
|
|
Ultra-High Transmission Coatings
|
optional at time of purchase
|
optional at time of purchase
|
optional at time of purchase
|
| Limiting
Visual Stellar Magnitude |
11.7 |
12.1 |
12.5 |
|
Image Scale |
1.16?/inch |
0.99?/inch |
0.76?/inch |
| Maximum
Practical Visual Power |
325X |
420X |
500X |
|
Optical Tube Dimensions
(dia. x length) |
4.1" x 11" (10.4cm x 27.9cm) |
4.88" x 12.9" (12.4cm x 32.8cm) |
5.75" x 14.2" (14.6cm x 36cm) |
| Eyepiece
|
Super Pl?sl 26mm |
Super Pl?sl 26mm |
Super Pl?sl 26mm |
|
Secondary Mirror
Obstruction (dia.; %) |
1.1" (27.9mm); 9.6% |
1.32" (33.0mm); 9.4% |
1.55" (39.4mm); 9.6% |
| Telescope
Mounting |
Fork type; double
tine |
Fork type; double
tine |
Fork type; double
tine |
|
Setting Circle Diameters |
Dec.: 3.5"; R.A.: 7" |
Dec.: 3.81"; R.A.: 7.8" |
Dec.: 4.3"; R.A.: 9" |
|
Motor Drive System
|
DC servo motors
with encoders, both axes; 12-volts |
DC
servo motors with encoders, both axes; 12-volts |
DC servo motors
with encoders, both axes;12-volts |
|
Slow-Motion Controls |
Electric, 4-speed, both axes |
Electric, 4-speed, both axes |
Electric, 4-speed, both axes |
| Optional
Autostar Capability |
Yes |
Yes |
Yes |
|
Hemispheres of Operation |
North and South |
North and South |
North and South |
| Batteries
|
8 x AA |
3 x AA |
8 x AA |
|
Battery Life
(approx.) |
|
|
|
| with
Electronic Controller |
45 hrs.
|
45 hrs.
|
45 hrs. |
|
with Autostar
(optional) |
20 hrs. |
20 hrs. |
20 hrs. |
| Bearings
|
Nylon, both axes |
Dec: ball
bearings; R.A.: radial ball bearing |
Dec: ball
bearings; R.A.: ball bearings |
|
Materials: Tube body |
Aluminum |
Aluminum |
Aluminum |
|
Mounting |
steel-reinforced
high-impact ABS |
internal aluminum
structure with high-impact ABS |
internal aluminum
structure with high-impact ABS |
|
Primary
Mirror |
Pyrex ? glass |
Pyrex? glass |
Pyrex? glass |
|
Correcting Lens |
BK7 optical
glass,
Grade-A |
BK7 optical
glass, Grade-A |
BK7 optical
glass, Grade-A |
|
Telescope Dimensions |
15" x 7.3" x 8.5" |
17" x 8" x 10" |
19" x 8.9" x 10.8" |
| Telescope
Net Weight |
7.8 lbs (3.5 kg) |
13.5 lbs. (6.1
kg) |
15.2 lbs. (6.9
kg) |
|
Telescope Shipping Weight
|
12.4 lbs (5.6 kg) |
18.4 lbs (8.3 kg) |
25.2 lbs. (11.4 kg) |
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