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Optical Tubes Only (OTA)

An optical tube assembly, or OTA, is the telescope without a mount or tripod. It is how most experienced observers and imagers buy, because they already own a mount or want to choose it separately. This collection brings together every tube we sell on its own: refractors from Askar, William Optics, Sky-Watcher, Explore Scientific, Tele Vue, SVBONY, SharpStar and ZWO, Celestron SCT, EdgeHD and RASA tubes, Newtonians and Cassegrains from Orion Optics UK and iOptron, and Maksutovs from several makers.

Buying a tube alone means you need to think about how it attaches to the mount and what it needs at the back end. That is where we can save you a second order.

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CA$1,679.00 - CA$1,679.00
CA$1,679.00
CA$1,679.00 - CA$1,679.00
CA$1,679.00

Askar 103APO f/6.8 Triplet

103mm Aperture Triplet Air-Spaced APO Objective 700.4mm Focal Length f/6.8 Native Focal Ratio Includes One ED Glass Element for Superb Color Corre...

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CA$1,679.00 - CA$1,679.00
CA$1,679.00
CA$1,679.00 - CA$1,679.00
CA$1,679.00
CA$3,219.00 - CA$3,219.00
CA$3,219.00
CA$3,219.00 - CA$3,219.00
CA$3,219.00

Askar 107PHQ f/7 Quadruplet APO

107mm Aperture Quadruplet APO Optical Design 749mm Focal Length at f/7 44mm Corrected Image Circle for Full-Frame Sensors Integrated Field Flatten...

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CA$3,219.00 - CA$3,219.00
CA$3,219.00
CA$3,219.00 - CA$3,219.00
CA$3,219.00
CA$2,099.00 - CA$2,099.00
CA$2,099.00
CA$2,099.00 - CA$2,099.00
CA$2,099.00

Askar 111F Flat-Field Astrograph

111mm Aperture 766mm Focal Length (f/6.9) Quadruplet Air-Spaced APO Design with ED Glass 44mm Corrected Image Circle Integrated Field Flattener Ne...

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CA$2,099.00 - CA$2,099.00
CA$2,099.00
CA$2,099.00 - CA$2,099.00
CA$2,099.00
CA$2,379.00 - CA$2,379.00
CA$2,379.00
CA$2,379.00 - CA$2,379.00
CA$2,379.00

Askar 120APO f/7 Triplet

120mm Aperture Triplet Air-Spaced APO Objective Includes One ED Glass Element for Superb Color Correction 840mm Focal Length at a Native f/7 Focal...

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CA$2,379.00 - CA$2,379.00
CA$2,379.00
CA$2,379.00 - CA$2,379.00
CA$2,379.00
CA$4,899.00 - CA$4,899.00
CA$4,899.00
CA$4,899.00 - CA$4,899.00
CA$4,899.00

Askar 130PHQ f/7.7 Quadruplet APO

130mm Aperture Quadruplet APO Optics 1000mm Focal Length at f/7.7 Built-in Field Flattener 60mm Corrected Image Circle Total Assembled Weight of 1...

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CA$4,899.00 - CA$4,899.00
CA$4,899.00
CA$4,899.00 - CA$4,899.00
CA$4,899.00
Askar 131F Flat-Field APO Refractor
CA$2,799.00 - CA$2,799.00
CA$2,799.00
CA$2,799.00 - CA$2,799.00
CA$2,799.00

Askar 131F Flat-Field APO Refractor

131mm Aperture 983mm Focal Length (f/7.5) Quadruplet Air-Spaced APO Optical Design Includes One ED Glass Element 44mm Full-Frame Image Circle Inte...

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CA$2,799.00 - CA$2,799.00
CA$2,799.00
CA$2,799.00 - CA$2,799.00
CA$2,799.00
CA$3,499.00 - CA$3,499.00
CA$3,499.00
CA$3,499.00 - CA$3,499.00
CA$3,499.00

Askar 140APO f/7 Triplet

140mm Aperture 980mm Focal Length (f/7) Triplet Air-Spaced APO Objective with ED Glass OTA Weight: 9.2kg | Total Weight: 10.9kg 125mm Retractable ...

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CA$3,499.00 - CA$3,499.00
CA$3,499.00
CA$3,499.00 - CA$3,499.00
CA$3,499.00
Askar 151PHQ f/7 Quadruplet Astrograph
CA$6,299.00 - CA$6,299.00
CA$6,299.00
CA$6,299.00 - CA$6,299.00
CA$6,299.00

Askar 151PHQ f/7 Quadruplet Astrograph

151mm Aperture Quadruplet APO Optics 1057mm Focal Length at f/7 Integrated Flattener for a 60mm Image Circle Includes 2 ED Glass Elements for Colo...

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CA$6,299.00 - CA$6,299.00
CA$6,299.00
CA$6,299.00 - CA$6,299.00
CA$6,299.00
CA$5,383.00 - CA$5,383.00
CA$5,383.00
CA$5,383.00 - CA$5,383.00
CA$5,383.00

Askar 160APO f/7 Triplet

160mm Aperture Triplet Air-Spaced APO Objective 1120mm Focal Length at f/7 Includes One ED Glass Element for Color Correction Retractable Dew Shie...

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CA$5,383.00 - CA$5,383.00
CA$5,383.00
CA$5,383.00 - CA$5,383.00
CA$5,383.00
CA$7,391.00 - CA$7,391.00
CA$7,391.00
CA$7,391.00 - CA$7,391.00
CA$7,391.00

Askar 185APO f/7 Triplet

185mm Aperture Triplet APO Objective 1295mm Focal Length at f/7 Includes one ED Glass Element for Color Correction 95mm Retractable Rear Tube for ...

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CA$7,391.00 - CA$7,391.00
CA$7,391.00
CA$7,391.00 - CA$7,391.00
CA$7,391.00
Askar 203APO f/7 Triplet APO Refractor
CA$12,011.00 - CA$12,011.00
CA$12,011.00
CA$12,011.00 - CA$12,011.00
CA$12,011.00

Askar 203APO f/7 Triplet APO Refractor

203mm Aperture Triplet Air-Spaced APO Objective 1421mm Focal Length at f/7 Includes one ED (Extra-Low Dispersion) Glass Element Retractable Tube D...

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CA$12,011.00 - CA$12,011.00
CA$12,011.00
CA$12,011.00 - CA$12,011.00
CA$12,011.00
CA$419.00 - CA$419.00
CA$419.00
CA$419.00 - CA$419.00
CA$419.00

Askar 50P f/3.8 Quadruplet APO Telescope

50mm Aperture Quadruplet APO Optics Ultra-Fast f/3.8 Focal Ratio 190mm Focal Length Natively Flat Field for APS-C Sensors Standard 55mm Back Focus...

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CA$419.00 - CA$419.00
CA$419.00
CA$419.00 - CA$419.00
CA$419.00
Askar 60F Flat-Field Astrograph
CA$699.00 - CA$699.00
CA$699.00
CA$699.00 - CA$699.00
CA$699.00

Askar 60F Flat-Field Astrograph

60mm Aperture Quadruplet APO Optics 408mm Focal Length (f/6.8) 44mm Full-Frame Corrected Image Circle Integrated Field Flattener 2.4-inch Dual-Spe...

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CA$699.00 - CA$699.00
CA$699.00
CA$699.00 - CA$699.00
CA$699.00
Askar 65PHQ f/6.4 Quintuplet Flat-Field Astrograph
CA$1,259.00 - CA$1,259.00
CA$1,259.00
CA$1,259.00 - CA$1,259.00
CA$1,259.00

Askar 65PHQ f/6.4 Quintuplet Flat-Field Astrograph

65mm Aperture Quintuplet APO Optical Design 416mm Focal Length at f/6.4 Built-in Field Flattener with a 44mm Image Circle 2.8kg Total Weight Inclu...

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CA$1,259.00 - CA$1,259.00
CA$1,259.00
CA$1,259.00 - CA$1,259.00
CA$1,259.00
CA$923.00 - CA$923.00
CA$923.00
CA$923.00 - CA$923.00
CA$923.00

Askar 71F Quadruplet Flat-Field APO f/6.9

71mm Aperture Quadruplet Air-Spaced APO 490mm Focal Length at f/6.9 44mm Full-Frame Corrected Image Circle Integrated Field Flattener Design 2.4-i...

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CA$923.00 - CA$923.00
CA$923.00
CA$923.00 - CA$923.00
CA$923.00
CA$559.00 - CA$559.00
CA$559.00
CA$559.00 - CA$559.00
CA$559.00

Askar 80ED f/7 Doublet

80mm Aperture 560mm Focal Length (f/7) Doublet Objective with ED Glass 1.7 kg OTA Weight 2" Dual-Speed Rack & Pinion Focuser Optimized for APS...

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CA$559.00 - CA$559.00
CA$559.00
CA$559.00 - CA$559.00
CA$559.00
CA$2,099.00 - CA$2,099.00
CA$2,099.00
CA$2,099.00 - CA$2,099.00
CA$2,099.00

Askar 80PHQ f/7.5 Quadruplet APO

80mm Aperture 600mm Focal Length (f/7.5) Quadruplet APO Optics with 2 ED Elements 44mm Full-Frame Corrected Image Circle 3.9kg Optical Tube Weight...

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CA$2,099.00 - CA$2,099.00
CA$2,099.00
CA$2,099.00 - CA$2,099.00
CA$2,099.00
Askar 91F Flat-Field Astrograph
CA$1,399.00 - CA$1,399.00
CA$1,399.00
CA$1,399.00 - CA$1,399.00
CA$1,399.00

Askar 91F Flat-Field Astrograph

91mm Aperture Quadruplet APO Optics 609mm Focal Length at f/6.7 44mm Full-Frame Corrected Image Circle Integrated Field Flattener Design 3.92kg Ne...

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CA$1,399.00 - CA$1,399.00
CA$1,399.00
CA$1,399.00 - CA$1,399.00
CA$1,399.00
CA$1,329.00 - CA$1,329.00
CA$1,329.00
CA$1,329.00 - CA$1,329.00
CA$1,329.00

Askar FRA300 Pro 60mm f/5 Quintuplet APO

60mm Quintuplet APO Astrograph 300mm Focal Length at a Fast f/5 Focal Ratio 44mm Full-Frame Corrected Image Circle Integrated Petzval Corrector De...

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CA$1,329.00 - CA$1,329.00
CA$1,329.00
CA$1,329.00 - CA$1,329.00
CA$1,329.00
CA$1,679.00 - CA$1,679.00
CA$1,679.00
CA$1,679.00 - CA$1,679.00
CA$1,679.00

Askar FRA400 72mm f/5.6 Quintuplet APO

72mm Aperture Quintuplet APO Lens 400mm Focal Length at f/5.6 44mm Natively Flat Image Circle 140mm Available Back Focus from M68x1 Thread 3" Rack...

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CA$1,679.00 - CA$1,679.00
CA$1,679.00
CA$1,679.00 - CA$1,679.00
CA$1,679.00
CA$1,253.00 - CA$1,253.00
CA$1,253.00
CA$1,253.00 - CA$1,253.00
CA$1,253.00

Askar FRA400C 72mm f/5.6 Quintuplet APO

72mm Aperture Quintuplet APO Optics 400mm Focal Length at f/5.6 Covers a 44mm Full-Frame Image Circle Integrated 17-Blade Aperture (f/5.6-f/22) 2....

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CA$1,253.00 - CA$1,253.00
CA$1,253.00
CA$1,253.00 - CA$1,253.00
CA$1,253.00
CA$2,799.00 - CA$2,799.00
CA$2,799.00
CA$2,799.00 - CA$2,799.00
CA$2,799.00

Askar FRA500 90mm f/5.6 Quintuplet APO

90mm Aperture Quintuplet APO Optics 500mm Focal Length at f/5.6 Massive 55mm Natively Flat Image Circle Includes Two ED Glass Elements Total Assem...

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CA$2,799.00 - CA$2,799.00
CA$2,799.00
CA$2,799.00 - CA$2,799.00
CA$2,799.00
CA$3,639.00 - CA$3,639.00
CA$3,639.00
CA$3,639.00 - CA$3,639.00
CA$3,639.00

Askar FRA600 108mm f/5.6 Quintuplet APO

108mm Aperture 600mm Focal Length (f/5.6) Quintuplet Flat-Field APO Optical Design 66mm Corrected Image Circle 6.5kg Total Weight (including tube ...

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CA$3,639.00 - CA$3,639.00
CA$3,639.00
CA$3,639.00 - CA$3,639.00
CA$3,639.00
CA$1,538.00 - CA$1,538.00
CA$1,538.00
CA$1,538.00 - CA$1,538.00
CA$1,538.00

Askar N160 f/3.6 Newtonian

160mm Aperture Parabolic Mirror f/3.4 Corrected Focal Ratio with Included 0.95x Corrector 544mm Corrected Focal Length Carbon Fiber Tube Construct...

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CA$1,538.00 - CA$1,538.00
CA$1,538.00
CA$1,538.00 - CA$1,538.00
CA$1,538.00

Before You Order an OTA

  • Dovetail standard: Vixen-style (about 44 mm) bars suit small and medium mounts. Losmandy-style (about 75 mm) bars are used on heavier tubes and mounts. Check what your saddle accepts, or add a dual saddle. See dovetail plates.
  • Rings or no rings: Many refractors come with rings and a short bar. Newtonians and large tubes may need tube rings sized to the exact outside diameter.
  • Real payload: Tube weight is only the start. Add rings, bar, finder, diagonal or camera, guide scope and dew control.
  • Back end: Visual use needs a diagonal and eyepieces. Imaging needs the correct corrector and adapters for your camera.
  • Collimation needs: Refractors and Maks rarely need it. Newtonians, RCs and SCTs need occasional adjustment.

What We Work Out With You

  • Mount compatibility: We check the dovetail standard, saddle and total payload against your mount.
  • Counterweight and balance: Long or heavy tubes can need extra counterweight or a longer bar. We check this before shipping.
  • Complete back end: We list the diagonal, corrector, spacers and adapters so the tube works the day it arrives.

Optical Tubes: Frequently Asked Questions

Will this tube fit my mount?

If the mount's saddle accepts the dovetail and the total payload is within its imaging or visual capacity, yes. Send us the mount model and we will confirm.

Does the OTA include a finder or diagonal?

It varies by model. Each product page lists what is included. Ask us if anything is unclear.

Should I buy a kit or an OTA?

If you do not own a suitable mount, a kit is usually better value. If you plan to upgrade the mount later, buy the OTA and the mount you really want.

Adding a tube to your setup?

Send us your mount model and planned camera or eyepieces. We will confirm fit and list everything you need.