7. Specifications

Optical Tube Assembly (OTA)

Primary mirror:

356mm (14.0") diameter

 

reflective surface, low thermal

 

expansion optical glass,

 

parabolic, center marked

Focal length:

1650mm

Focal ratio:

f/4.6

Primary mirror cell:

18-point flotation, 3 spring-

 

loaded collimation knobs

Secondary mirror:

80mm minor axis, low thermal

 

expansion optical glass

Secondary mirror holder:

4-vane spider assembly, 0.7mm

 

thick spider vanes, 3 SHCS for

 

tilt adjustment

Mirror coatings:

Enhanced reflectivity (94%)

 

aluminum with SiO2 overcoat

Focuser:

Dual speed Crayford, 11:1

 

fine focus knob, accepts 2"

 

and 1.25" eyepieces, all metal

 

construction

Optical tube design:

Truss tube

Truss poles:

8 total (4 truss pole assembles

 

with 2 poles each), 1.0" outer

 

diameter, aluminum black

 

anodized, captive assembly

 

hardware

Navigation knob:

Included

Optical tube material:

Rolled steel, 1.0mm thick

Tube outer diameter:

412mm (16.2")

OTA weight, assembled:

69.25 lbs.

OTA weight, disassembled: Lower tube section, 52.9 lbs. Upper tube section, 9.4 lbs. Truss pole assemblies, 6.9 lbs.

OTA length, assembled:

61"

OTA length, disassembled: Lower tube section, 21.75" long; Upper tube section, 8.1" long; Truss pole assemblies, 33.75" long

Mount

 

Dobsonian base:

Collapsible design,

 

CorrecTension altitude

 

tensioning, side brace supports,

 

carry handle

Azimuth bearing material:

Virgin Teflon on Ebony Star

 

laminate

Altitude bearing material:

Ultra-high molecular weight

 

(UHMW) polyethylene on ABS

 

plastic

Altitude bearing diameter:

8.0"

IntelliScope functionality:

Computerized Object Locator

 

system included, 14,000+

 

object database

Base weight:

45 lbs., assembled

Approximate base

 

dimensions:

29" diameter x 27" tall

Accessories

 

2" Eyepiece:

35mm Deep View, 2", multi-

 

coated, threaded for Orion filters

1.25" Eyepiece:

10mm Sirius Plössl, 1.25",

 

multi-coated, threaded for Orion

 

filters

Eyepiece magnifications:

47.1x and 165x

Finder scope:

9x power, 50mm aperture,

 

achromatic, crosshairs, 5° field

 

of view

Finder scope bracket:

Spring-loaded X-Y adjustment,

 

dovetail base

Eyepiece rack:

Holds three 1.25" eyepieces

 

and one 2" eyepiece

Cooling accelerator fan:

Included, runs off of 12V DC

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Orion 9791 instruction manual Specifications, Optical Tube Assembly OTA, Mount, Accessories