Borg 90FL f/4 Drawtube Astrograph OTA Set

Borg 90FL f/4 Drawtube Astrograph OTA Set


Special - Shipped 10-20 working days.

Model:  borg_90fl_f4_drawtube_set
Part Number:  6690
Brand:  Borg



  • 2591 - 90FL Flourite Objective
  • 7101 - 80mm Dia. 100mm Tube
  • 7780 - Drawtube Holder DX
  • 7790 - Drawtube DX
  • 7835 - Helical Focuser M
  • 7872 - 0.72x Quadruplet Reducer

Japanese made Borg 90FL f/4 drawtube astrograph features a premium quality Fluorite objective from Canon with 80mm tube diameter.

The 'drawtube' package features a drawtube for easier focusing and doesn't include the M57 camera rotator found in the regular astrograph package. To use visually you can simply remove the reducer and replace with a 2" eyepiece holder available separately such as 7504.

The addition of the drawtube makes this useful for use as a telephoto lens for wildlife photograph as it allows focusing at various distances - the pure astrograph set is designed primarily for focusing at infinity.

Includes a Borg Helical focuser for precise dependable focusing. 

Modular Borg design allows you to reconfigure the scope for visual observing or to disassemble it for ultra portability.


  • Aperture: 90mm
  • Focal length: 360mm
  • F-ratio: 4
  • Lens configuration: 6 elements in 5 groups
  • Coating: Fully multi-coated
  • Physical length: 400mm
  • Tube diameter: 80mm
  • Weight: 1.9kg
  • Filter: 82mm (front cap) & 48mm in front of reducer
  • Parts included: 2591, 7101, 7780, 7790, 7835 & 7872

90mm Fluorite Objective

  • Focal length : 500mm
  • F-ratio : 5.6
  • Weight : 950g
  • Length : 145mm

Precision helical focuser

  • Light path: 63mm to 82mm
  • OD: 77mm
  • ID: 56mm
  • Weight: 320g

0.72x Reducer

  • Four-element reducer
  • Back focus distance: 60mm
  • Image coverage: Full frame
  • Objective side interface: M57 male
  • Camera side interface: M57 female

Telescope Field of View Simulator

There are currently no specifications available for this product.

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