Borg Optical Tube Assemblies.

Borg Series 80 Optical Tube Assemblies comprise the following components:

A. Objective Lens [50ED, 77Ach, 77ED, 100Ach, 101ED]
B. 80mm diameter, 205mm long tube [7800]
C. Draw tube holder [7749]
D. Helical focuser M [7835]
E. 2" Eyepiece holder S [7508}
F. 2" Eyepiece holder L [7509}
G. M57 to M36.4 Adaptor [7522]
H. 1.25" Eyepiece holder [7317]
This will enable the OTA to accept 2" or 1.25" diagonals/eyepieces.
Use 7080 Tube Band M Set to attach the OTA to a conventional mount & tripod (see Mounts
& Tripods for Borg Telescopes section for details).

Borg 77Ach OTA - Eco-Borg, Eco-priced.
This scope's newly designed achromat, using environmentally friendly Eco-glass, features a
spot size less than 10 microns between 630nm and the green region. Both chromatic and
spherical aberration are improved over the 76Ach. The 77Ach supercedes the 76Ach as
Borg's
entry level Series 80 telescope.

Specifications:
Aperture - 77mm
Focal Length - 500mm F6.5
Objective - Achromat, 2 elements in 1 group, fully coated
Tube Diameter - 80mm
OTA Length - 380mm
Total Weight - 1.6kg (3.5lbs)
Filter Thread - 77mm/82mm in front of objective and 52mm in 2" eyepiece holder

Price - £320.00

Borg 77ED Apochromatic OTA - Best selling OTA.
Borg's newest OTA. ED element allows high-power observing of the moon, planets, and
double stars. Borg's photo-visual design ensures high-quality images when used with a
reducer and flattener etc. 77mm and 82mm thread in front of objective for H-alpha filters.
Makes a great guide scope.

Specifications:
Aperture - 77mm
Focal Length - 500mm F6.5
Objective - Apochromat, 2 elements in 2 groups, fully multicoated
Tube Diameter - 80mm
OTA Length - 380mm
Total Weight - 1.7kg (3.7lbs)
Filter Thread - 77mm/82mm in front of objective and 52mm in 2" eyepiece holder

Price - £573.00

Borg 101ED Apochromat OTA - High-end Series 80 OTA.
This scope's objective is a redesigned version of the 100ED that takes advantage of the new
Eco-glass. This material improves visual performance, but still provides high image quality
when used with any of Borg's existing imaging correctors. The 101ED supercedes the 100ED
as Borg's premium 4 inch telescope. Upgradable to Series 115.

Specifications:
Aperture - 101mm
Focal Length - 640mm F6.3
Objective - Apochromat, 2 elements in 2 groups, fully multicoated
Tube Diameter - 80mm
OTA Length - 530mm
Total Weight - 2.3kg (5.1lbs)
Filter Thread - 52mm in 2" eyepiece holder

Price - £1123.00

See the review in the September 2006 issue of Sky at Night.

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