| |
| TELESCOPE |
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 |
1470mm
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
Plössl 26mm |
Super
Plössl 26mm |
Super
Plössl 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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