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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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ZWO FF90-APO 90mm Quadruplet Refractor F/6.8

90mm Aperture 609mm Focal Length (f/6.8) 4-Element Quadruplet Optical Design 44mm Full-Frame Image Circle 3" Dual-Speed Rack & Pinion Focuser ...

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CA$1,409.00
CA$1,409.00 - CA$1,409.00
CA$1,409.00
CA$1,268.00
CA$1,268.00 - CA$1,268.00
CA$1,268.00
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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.