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Refractors

Réfracteurs

Refractors earn their following through consistency. A sealed lens system holds collimation indefinitely, cools quickly, gives high-contrast views without a central obstruction, and — in modern apochromatic form — produces the clean, round stars that make wide-field astrophotography look effortless. David Astro carries refractors in Canada, from compact 50 mm travel astrographs to large apochromatic triplets, shipping from Canadian stock.

We image with refractors under Canadian skies and can speak to the practical differences between doublets and triplets, and between glass types, in terms of what actually shows in a finished image rather than what appears on a specification sheet.

Filtres

CA$6,304.00 - CA$8,162.00
CA$6,304.00 - CA$8,162.00
CA$6,304.00 - CA$8,162.00
CA$6,304.00

William Optics Fluorostar 132

Options available

APO de 132 mm Rapport focale rapide F/6.9 Portable et polyvalent Description Caractéristiques Dans la boite Libérez vot...

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CA$6,304.00 - CA$8,162.00
CA$6,304.00 - CA$8,162.00
CA$6,304.00 - CA$8,162.00
CA$6,304.00
CA$10,653.00 - CA$12,417.00
CA$10,653.00 - CA$12,417.00
CA$10,653.00 - CA$12,417.00
CA$10,653.00

William Optics Fluorostar 156

Options available

APO de 156 mm Rapport focale rapide F/6,7 Portable et polyvalent Description Caractéristiques Dans la boite Libérez vot...

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CA$10,653.00 - CA$12,417.00
CA$10,653.00 - CA$12,417.00
CA$10,653.00 - CA$12,417.00
CA$10,653.00
CA$2,877.00 - CA$3,033.00
CA$2,877.00 - CA$3,033.00
CA$2,877.00 - CA$3,033.00
CA$2,877.00

William Optics Fluorostar 91

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APO de 91 mm utilisant du verre FPL-53 Rapport focale rapide F/5.9 Portable et polyvalent Description Caractéristiques Dans la b...

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CA$2,877.00 - CA$3,033.00
CA$2,877.00 - CA$3,033.00
CA$2,877.00 - CA$3,033.00
CA$2,877.00
CA$1,515.00 - CA$1,515.00
CA$1,515.00
CA$1,515.00 - CA$1,515.00
CA$1,515.00

William Optics Gran Turismo 71 Triplet APO

WO-A-F71GTII-RD

Triplet APO de 71 mm Rapport focale rapide F/5.9 Portable et polyvalent Description Caractéristiques Dans la boite Libé...

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CA$1,515.00 - CA$1,515.00
CA$1,515.00
CA$1,515.00 - CA$1,515.00
CA$1,515.00
CA$3,033.00 - CA$3,033.00
CA$3,033.00
CA$3,033.00 - CA$3,033.00
CA$3,033.00

William Optics Gran Turismo WIFD 81

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APO de 81 mm Rapport focale rapide F/5.9 Portable et polyvalent Description Caractéristiques Dans la boite Libérez votr...

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CA$3,033.00 - CA$3,033.00
CA$3,033.00
CA$3,033.00 - CA$3,033.00
CA$3,033.00
CA$549.00 - CA$631.00
CA$549.00 - CA$631.00
CA$549.00 - CA$631.00
CA$549.00

William Optics Guide Star 61

Options available

Télescope réfracteur apochromatique à ouverture de 61 mm Instrument polyvalent pour l'astrophotographie de guidage et à grand champ ...

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CA$549.00 - CA$631.00
CA$549.00 - CA$631.00
CA$549.00 - CA$631.00
CA$549.00
CA$1,363.00 - CA$1,363.00
CA$1,363.00
CA$1,363.00 - CA$1,363.00
CA$1,363.00

William Optics MiniCat 51 WIFD f/3.5

WO-T-C-MINI-RD
3 en stock

51mm Aperture Diameter 178mm Focal Length f/3.5 Focal Ratio 6-Element Petzval Optical Design 43.2mm Full-Frame Image Circle WIFD Rack & Pinion...

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CA$1,363.00 - CA$1,363.00
CA$1,363.00
CA$1,363.00 - CA$1,363.00
CA$1,363.00
CA$5,793.00 - CA$5,793.00
CA$5,793.00
CA$5,793.00 - CA$5,793.00
CA$5,793.00

William Optics Pleiades 111 Astrographe F/4.8 7 éléments WIFD

WO-T-P-111BU

Conception du réfracteur APO à 7 éléments Rapport focale rapide F/4,8 Conception de champ d'image large (WIFD) Portable et polyvalent ...

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CA$5,793.00 - CA$5,793.00
CA$5,793.00
CA$5,793.00 - CA$5,793.00
CA$5,793.00
CA$27,597.00 - CA$27,597.00
CA$27,597.00
CA$27,597.00 - CA$27,597.00
CA$27,597.00

William Optics Pleiades 181 Astrograph F/5.5 7 éléments avec 3 lunettes ED

WO-T-P-181RD

APO à 7 éléments avec conception de réfracteur à 3 lunettes ED Rapport focale rapide F/5,5 Portable et polyvalent Description Car...

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CA$27,597.00 - CA$27,597.00
CA$27,597.00
CA$27,597.00 - CA$27,597.00
CA$27,597.00
CA$3,033.00 - CA$3,033.00
CA$3,033.00
CA$3,033.00 - CA$3,033.00
CA$3,033.00

William Optics Pleiades 68 Astrographe F/3.8 7 éléments WIFD

WO-T-P-68BU

Conception du réfracteur APO à 7 éléments Rapport focale rapide F/3,8 Conception du porte-oculaire interne WO (WIFD) Portable et polyvalent...

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CA$3,033.00 - CA$3,033.00
CA$3,033.00
CA$3,033.00 - CA$3,033.00
CA$3,033.00
CA$1,225.00 - CA$1,225.00
CA$1,225.00
CA$1,225.00 - CA$1,225.00
CA$1,225.00

William Optics Redcat 51 WIFD

WO-L-RC51RDIII
1 en stock

Lunette Petzval 51 mm à 4 éléments Distance focale de 250 mm - rapport focal f/4,9 Cercle d'image de 48 mm - Aucun aplatisseur de champ requi...

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CA$1,225.00 - CA$1,225.00
CA$1,225.00
CA$1,225.00 - CA$1,225.00
CA$1,225.00
CA$1,581.00 - CA$1,581.00
CA$1,581.00
CA$1,581.00 - CA$1,581.00
CA$1,581.00

William Optics RedCat 61 WIFD

WO-T-C-61RD
1 en stock

Lunette Petzval 51 mm à 4 éléments Focale de 300 mm - rapport focal f/4,9 Cercle d'image de 46 mm - Aucun aplatisseur de champ requis C...

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CA$1,581.00 - CA$1,581.00
CA$1,581.00
CA$1,581.00 - CA$1,581.00
CA$1,581.00
CA$2,013.00 - CA$2,013.00
CA$2,013.00
CA$2,013.00 - CA$2,013.00
CA$2,013.00

William Optics Redcat 71 WIFD

WO-T-C-71RDII

APO de 71 mm Rapport focale rapide F/4.9 Portable et polyvalent Description Caractéristiques Dans la boite Libérez votr...

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CA$2,013.00 - CA$2,013.00
CA$2,013.00
CA$2,013.00 - CA$2,013.00
CA$2,013.00
William Optics Ultra-Cat 131 f/4.9 Petzval Astrograph
CA$7,449.00 - CA$7,449.00
CA$7,449.00
CA$7,449.00 - CA$7,449.00
CA$7,449.00

William Optics Ultra-Cat 131 f/4.9 Petzval Astrograph

WO-T-C-131BR

131mm Aperture 648mm Focal Length (f/4.9) 5-Element Advanced Petzval Optical Design 60mm Flat-Field Image Circle Patented WIFD Internal Focuser 13...

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CA$7,449.00 - CA$7,449.00
CA$7,449.00
CA$7,449.00 - CA$7,449.00
CA$7,449.00
CA$5,517.00 - CA$5,517.00
CA$5,517.00
CA$5,517.00 - CA$5,517.00
CA$5,517.00

William Optics UltraCat 108 f/4.8 WIFD

WO-T-C-108BR
1 en stock

108mm Aperture, 5-Element Advanced Petzval Optical Design Fast f/4.8 Focal Ratio with 518mm Focal Length Massive 60mm Flat-Field Image Circle Pate...

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CA$5,517.00 - CA$5,517.00
CA$5,517.00
CA$5,517.00 - CA$5,517.00
CA$5,517.00
CA$1,929.00 - CA$1,929.00
CA$1,929.00
CA$1,929.00 - CA$1,929.00
CA$1,929.00

William Optics UltraCat 56 f/4.8 WIFD

WO-T-C-56BR
6 en stock

56mm Aperture, 269mm Focal Length (f/4.8) 5-Element Advanced Petzval Optical Design 50mm Image Circle for Full-Frame Sensors William Optics Intern...

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CA$1,929.00 - CA$1,929.00
CA$1,929.00
CA$1,929.00 - CA$1,929.00
CA$1,929.00
CA$3,033.00 - CA$3,033.00
CA$3,033.00
CA$3,033.00 - CA$3,033.00
CA$3,033.00

William Optics UltraCat 76 f/4.8 WIFD

WO-T-C-76BR
2 en stock

76 mm Aperture, 365 mm Focal Length (f/4.8) 5-Element Advanced Petzval Optical Design 50 mm Corrected Image Circle William Optics Internal Focusin...

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CA$3,033.00 - CA$3,033.00
CA$3,033.00
CA$3,033.00 - CA$3,033.00
CA$3,033.00
CA$962.00 - CA$962.00
CA$962.00
CA$962.00 - CA$962.00
CA$962.00

William Optics Zenithstar 61 II Doublet APO

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APO de 61 mm utilisant du verre FPL-53 Rapport focale rapide F/5.9 Portable et polyvalent Description Caractéristiques Dans la b...

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CA$962.00 - CA$962.00
CA$962.00
CA$962.00 - CA$962.00
CA$962.00
CA$1,398.00 - CA$1,515.00
CA$1,398.00 - CA$1,515.00
CA$1,398.00 - CA$1,515.00
CA$1,398.00

William Optics Zenithstar 81 WIFD Telescope

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Patented William Optics Internal Focus Design (WIFD) Rigid M92 Rear Thread with M63 Adapter Included Vixen/Arca-Swiss Dual-Sided Mounting Plate In...

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CA$1,398.00 - CA$1,515.00
CA$1,398.00 - CA$1,515.00
CA$1,398.00 - CA$1,515.00
CA$1,398.00
CA$2,109.00 - CA$2,109.00
CA$2,109.00
CA$2,109.00 - CA$2,109.00
CA$2,109.00

ZWO FF110-APO 110mm Quadruplet Refractor F/7.0

ZWO-FF110-APO
1 en stock

90mm Aperture 766mm Focal Length (f/7) 4-Element Apochromatic Optics Integrated Field Flattener 3-inch Dual-Speed Focuser 14.9 lb. Optical Tube We...

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CA$2,109.00 - CA$2,109.00
CA$2,109.00
CA$2,109.00 - CA$2,109.00
CA$2,109.00
CA$2,819.00 - CA$2,819.00
CA$2,819.00
CA$2,819.00 - CA$2,819.00
CA$2,819.00

ZWO FF131-APO 131mm Quadruplet Refractor F/7.5

ZWO-FF131-APO
1 en stock

131mm Aperture 983mm Focal Length (f/7.5) 4-Element Petzval Optical Design 3-inch Dual-Speed Rack & Pinion Focuser 20.7 lb. Optical Tube Assem...

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CA$2,819.00 - CA$2,819.00
CA$2,819.00
CA$2,819.00 - CA$2,819.00
CA$2,819.00
CA$849.00 - CA$849.00
CA$849.00
CA$849.00 - CA$849.00
CA$849.00

ZWO FF70-APO 70mm Quadruplet Refractor F/7.0

ZWO-FF70-APO
2 en stock

70mm Aperture 490mm Focal Length (f/7) 4-Element Quadruplet Optical Design Integrated Field Flattener 2.4" Dual-Speed Rack & Pinion Focuser 6....

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CA$849.00 - CA$849.00
CA$849.00
CA$849.00 - CA$849.00
CA$849.00
CA$1,409.00 - CA$1,409.00
CA$1,409.00
CA$1,409.00 - CA$1,409.00
CA$1,409.00

ZWO FF90-APO 90mm Quadruplet Refractor F/6.8

ZWO-FF90-APO

90mm Aperture 609mm Focal Length (f/6.8) 4-Element Quadruplet Optical Design 3" Dual-Speed Rack & Pinion Focuser 9.97 lb. Optical Tube Assembl...

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CA$1,409.00 - CA$1,409.00
CA$1,409.00
CA$1,409.00 - CA$1,409.00
CA$1,409.00

Doublets, Triplets and Glass Types

The purpose of an apochromatic design is to bring three wavelengths to a common focus, eliminating the violet halo that achromatic refractors show on bright stars. How well it does that depends on the glass and the number of elements.

  • ED doublets: Two elements with one extra-low dispersion element. Lighter, less expensive, and excellent for imaging, with a small residual colour that is rarely visible in processed images.
  • Apochromatic triplets: Three elements giving near-complete colour correction, preferred for high-contrast visual observing and for imaging bright stars without halos. Heavier and slower to cool.
  • Petzval designs: Four-element optics with the field correction built in, so no separate flattener is needed and back-focus is fixed by the manufacturer — the simplest path to flat fields.
  • Achromatic refractors: Two-element crown and flint designs, excellent value for lunar, planetary and general visual use where some colour fringing on bright objects is acceptable.
  • Focal ratio: Fast refractors around f/5 give wide fields and short exposures; f/7 and slower give more image scale and are more forgiving of corrector spacing.
  • Matched correctors: Most refractors need a flattener or reducer designed for that specific model, spaced to its exact back-focus.

Why Choose David Astro for Refractors

A refractor is usually bought as the centre of an imaging system, so it should be specified alongside the mount and camera rather than on its own.

  • Corrector matched at the point of sale: We identify the flattener or reducer designed for your specific tube and supply the spacers to hit its back-focus exactly.
  • Focuser load assessed: We check that the stock focuser will carry your intended camera train without slip, and recommend an upgrade only when it genuinely will not.
  • Authorized dealer: Full manufacturer warranty and verified authenticity, with service handled inside Canada.
  • Ships from Canadian stock: No duties or brokerage fees for Canadian buyers, and no extra border handling for a precision optic.
  • Support after first light: Help with spacing, tilt and star shape diagnosis once the telescope is on the sky.

Refractors in Canada — Frequently Asked Questions

Doublet or triplet for imaging?
A good ED doublet is entirely sufficient for most deep-sky imaging and is lighter on the mount. A triplet shows its advantage on bright stars and in high-contrast visual use, at meaningful extra weight and cost.
Do I need a field flattener?
For imaging with anything larger than a small sensor, yes — a two-element refractor has a curved focal plane and corners will show elongated stars without one. Petzval designs have it built in.
How long does a refractor take to cool?
A small doublet is usable almost immediately. A large triplet can take 45 minutes or more to stabilize in Canadian winter conditions, and imaging before it does will show soft, bloated stars.
Is a small refractor enough for deep sky?
Yes, given integration time. A 60 to 80 mm apochromat on a good mount produces excellent wide-field images; total exposure time substitutes for aperture in imaging in a way it cannot for visual work.

Specifying a refractor?

Tell us your mount, camera and targets and we will match the tube and its corrector. Canadian stock, no surprise duties.